Learn Hardcore Portuguese (Portugal): Quando a melodia é simples, consigo seguir a guitarra facilmente. - When the melody is simple, I can follow the guitar easily.

Using se would make it clearly conditional (If the melody is simple), focusing on the condition rather than the time. It would still be grammatically correct, but slightly different in nuance:

Quando a melodia é simples… = whenever that happens (habit/rule).
Se a melodia é simples… = if that happens (condition; less common in this habitual sense).

So quando is the natural choice for a general rule tied to a time situation.

Why is it é simples and not está simples?

This is ser vs estar:

ser (é) is used for characteristics seen as inherent, typical, or defining.
estar (está) is used for temporary states, situations, or results.

A melodia é simples presents simplicity as the kind of melody we are talking about in that situation – a characteristic of that melody (or of melodies of that type).

You could say A melodia está simples, but that would sound more like:

the melody is unusually or temporarily simple,
or it has been made simple (e.g. a simplified arrangement).

In this context, é simples (with ser) is the default, neutral choice.

Why is the present tense used (é, consigo, seguir) instead of something like for or conseguirei?

Portuguese uses the present indicative for:

General truths or habits
That is the case here:
- Quando a melodia é simples, consigo seguir a guitarra facilmente.
  = Whenever the melody is simple, I can follow the guitar easily (habitual rule).
Future time introduced by words like quando
When talking about a specific future time, Portuguese typically uses present or future subjunctive, not will:
- Quando a melodia for simples, vou conseguir seguir a guitarra.
  (When the melody is simple [in the future], I’ll be able to follow the guitar.)

In your sentence, the speaker is stating a general ability, so the simple present é / consigo / seguir is exactly right.

What exactly does consigo mean here, and how is it different from posso?

Here consigo is the 1st person singular of conseguir (present indicative):

conseguir ≈ to manage to, to succeed in, to be able to (after some effort)
consigo = I manage / I am able (to)

So:

consigo seguir a guitarra ≈ I manage to follow the guitar, I’m able to keep up with the guitar.

posso, from poder, has a broader meaning:

poder = to be able to, can, may (possibility or permission).
- Posso seguir a guitarra can mean I am able to follow the guitar,
- but in other contexts it can also mean I’m allowed to follow… or It’s possible for me to follow…

Nuance:

consigo – emphasizes actual ability / success at doing it (often despite some difficulty).
posso – emphasizes possibility or permission.

In this sentence, consigo is more natural because it talks about your practical ability to keep up with the guitar when the melody is simple.

Note: consigo can also mean with him/her/you (formal) (e.g. Vou consigo = I’ll go with you/with him), but in your sentence it is clearly the verb conseguir, because it is followed by an infinitive (seguir).

Why is there no eu in consigo seguir a guitarra?

Portuguese is a pro‑drop language: subject pronouns are often omitted because the verb ending already shows the subject.

consigo already encodes eu (1st person singular).
Eu consigo seguir a guitarra is also correct, but eu is only used when you want to:
- add emphasis (e.g. contrasting with someone else: Eu consigo, ele não.),
- or avoid ambiguity.

In a neutral sentence, Quando a melodia é simples, consigo seguir a guitarra facilmente sounds perfectly natural without eu.

Is seguir a guitarra natural Portuguese, or would something else be more idiomatic?

seguir a guitarra is understandable and acceptable. It means:

to follow the guitar, in the sense of following what the guitar is playing, keeping up with it.

Other very common options in a musical context are:

acompanhar a guitarra – to accompany the guitar (play along with it).
seguir a música – to follow the music (more general).
acompanhar a música – to accompany / keep up with the music.

So, depending on the exact idea:

Focusing on the guitar line: seguir a guitarra or acompanhar a guitarra.
Focusing on the overall piece: seguir a música or acompanhar a música.

Your original phrase is fine; some speakers might slightly prefer acompanhar in this context.

Why is it a guitarra and not just seguir guitarra?

Portuguese normally uses the definite article with musical instruments when speaking about playing or following them:

tocar a guitarra – to play (the) guitar
ouvir o piano – to listen to (the) piano
seguir a guitarra – to follow (the) guitar

Key points:

a guitarra here refers to the guitar part in that piece of music, understood from context.
Omitting the article (seguir guitarra) is not standard; it sounds unnatural or foreign.
If you wanted to stress an unspecified guitar you could use uma guitarra (indefinite), but for the instrument line being played now, a guitarra is the default.

This is a big difference from English, where we often drop the article (play guitar). In European Portuguese you almost always say tocar a guitarra, tocar o piano, etc.

How does facilmente work grammatically, and how is it formed from fácil?

facilmente is an adverb of manner, modifying seguir (to follow). It tells us how you follow the guitar.

Formation:

Many adverbs of manner in Portuguese are formed from the feminine singular form of an adjective
- ‑mente:
  - rápido → rapidamente
  - claro → claramente
  - fácil → facilmente

Note the spelling: facilmente (no accent). The accent on fácil doesn’t carry over; fácilmente is incorrect.

You can often paraphrase ‑mente adverbs with com + noun:

facilmente ≈ com facilidade (with ease).

So you could also say:

…consigo seguir a guitarra com facilidade.

Both are correct; facilmente is a bit more compact, com facilidade slightly more formal/emphatic.

Can facilmente go in other positions in the sentence?

Yes. Adverbs like facilmente are quite flexible in Portuguese. All of these are possible:

Quando a melodia é simples, consigo seguir a guitarra facilmente.
Quando a melodia é simples, consigo seguir facilmente a guitarra.
Quando a melodia é simples, facilmente consigo seguir a guitarra.

Nuance:

End of the clause (…guitarra facilmente) is the most neutral/common.
Just before the verb phrase (Facilmente consigo…) puts extra emphasis on how easy it is.
Between verb and object (seguir facilmente a guitarra) is also correct and sounds natural.

So your version is fine, and moving facilmente mostly just changes emphasis, not meaning.

Why is there a comma after Quando a melodia é simples? Could we leave it out?

In standard Portuguese punctuation, you should use a comma between:

a subordinate clause (introduced by quando)
and the main clause

when the subordinate clause comes first:

Quando a melodia é simples, consigo seguir a guitarra facilmente.

Rules:

Subordinate clause first → comma is required.
Main clause first → comma is usually omitted:
- Consigo seguir a guitarra facilmente quando a melodia é simples.

So in your sentence, leaving the comma out would normally be treated as a punctuation mistake, even though the meaning is still clear.

Would Brazilians say this the same way, or are there differences between European and Brazilian Portuguese?

The sentence is perfectly understandable in both varieties, but there are some typical differences in choice of words:

In European Portuguese (Portugal), your sentence is very natural as is.
In Brazilian Portuguese, people would more commonly say for guitar:
- violão (for acoustic guitar)
- guitarra mainly for electric guitar

A Brazilian version might often look like:

Quando a melodia é simples, eu consigo acompanhar o violão com facilidade.

Differences you see there:

acompanhar instead of seguir – very common in Brazil for playing along with.
o violão instead of a guitarra (if it’s an acoustic guitar).
explicit eu is more frequent in speech in Brazil, though still optional.

Grammatically, though, your original sentence works fine in both varieties.

What is the difference between melodia and música in this context?

These two words are related but not the same:

melodia = the tune, the main line of notes you could sing or hum.
música = the whole piece of music / song (melody + harmony + rhythm, etc.), or music in general.

In your sentence:

Quando a melodia é simples… – you are talking about the tune itself being simple (the sequence of notes).
If you said Quando a música é simples…, it would refer more to the entire piece being simple (structure, chords, rhythm, etc.), and would sound a bit vaguer.

So melodia is the precise choice when you really mean the melodic line.