Learn Hardcore Portuguese (Brazil): Minha agenda está cheia esta semana, mas no domingo eu posso descansar. - My planner is full this week, but on Sunday I can rest.

agenda usually means a planner, diary, or schedule (your list of appointments).
It can be a physical object (a paper planner) or your schedule in general.

So minha agenda está cheia is closer to my schedule is full than to my agenda is full in English.

Why is it minha agenda está cheia and not minha agenda é cheia?

Portuguese uses estar for temporary or current states, and ser for more permanent or defining characteristics.

minha agenda está cheia = my schedule is (temporarily) full (for now / this week).
minha agenda é cheia would suggest that your schedule is always full, as a general characteristic of your life.

In this context, we’re talking about this week, so está cheia is the natural choice.

Why is it cheia and not cheio after agenda?

Adjectives in Portuguese agree in gender and number with the noun they describe.

agenda is a feminine singular noun (a agenda).
So the adjective must also be feminine singular: cheia.

If it were a masculine noun, e.g. o calendário, you’d say:

meu calendário está cheio (masculine singular).

What exactly does esta semana mean, and how is it different from essa semana?

Both are very close in meaning, but there is a nuance:

esta semana = this week (more “right here, the current week we’re in”).
essa semana = also often used as “this week” in Brazil, especially in speech, but originally more like that week (a bit less “right here”).

In everyday Brazilian Portuguese:

People say essa semana a lot for this week, and it sounds very natural.
esta semana sounds a bit more formal/careful, but is completely correct.

In your sentence, esta semana is perfectly fine and clear: this week.

Why is there no article before esta semana? Why not a esta semana?

With demonstratives like este/esta/esse/essa, you normally don’t use a definite article in this kind of expression:

esta semana = this week
essa semana = that/this week
a semana = the week

So:

esta semana (no article) is correct.
a esta semana would sound wrong or very unnatural here.

What does no in no domingo mean exactly?

no is a contraction:

em (in / on) + o (the, masculine singular) → no

So literally:

no domingo = em + o domingo = “on the Sunday” → on Sunday.

Similarly:

na segunda-feira = em + a segunda-feira = on Monday
no sábado = on Saturday

Can you say just domingo eu posso descansar without no?

Yes, you can. Both are possible:

no domingo eu posso descansar = on Sunday I can rest
domingo eu posso descansar = Sunday I can rest / I can rest Sunday

no domingo is a bit more explicit and is the most neutral, but dropping the preposition in informal speech is also common and understood.

Why is the word order no domingo eu posso descansar and not eu posso descansar no domingo?

Both orders are correct:

no domingo eu posso descansar
eu posso descansar no domingo

The difference is about emphasis, not grammar:

Starting with no domingo puts focus on Sunday:
- As for Sunday, that’s when I can rest.
Ending with no domingo sounds more neutral:
- I can rest (when?) on Sunday.

In conversation, you’ll hear both. Your sentence just happens to emphasize Sunday a bit.

Why is the subject pronoun eu used? Isn’t it often dropped in Portuguese?

Yes, in Portuguese the subject pronoun is often omitted, because the verb ending already shows who the subject is.

So you could say:

no domingo posso descansar (without eu) – totally correct.

Using eu can:

add a bit of emphasis: I can rest (even if others can’t), or
simply be the speaker’s natural style (some people use pronouns more often).

Both versions sound natural in Brazilian Portuguese.

What is the nuance of posso descansar compared to something like vou descansar?

They express different ideas:

posso descansar = I can rest / I am able/allowed to rest
- Focus on possibility, availability, permission.
vou descansar = I’m going to rest / I will rest
- Focus on a plan or decision.

In the sentence:

no domingo eu posso descansar suggests:
- My schedule allows me to rest Sunday.
- It’s possible for me to rest then.

If you said:

no domingo eu vou descansar, it would sound more like a decision/plan:
- On Sunday, I’m going to rest.

In English we usually say my schedule is full. Could you say meu horário está cheio or minha programação está cheia instead of minha agenda está cheia?

You can, but they’re not exact replacements:

minha agenda está cheia
- Very common, natural. Implies many appointments/commitments.
meu horário está cheio
- Understandable, but slightly less common in this exact form. More natural would be:
- meu horário está todo preenchido / meu horário está cheio de compromissos.
minha programação está cheia
- Sounds more like your planned activities (e.g. for a trip or event), not day‑to‑day work schedule.

For normal weekly busyness, minha agenda está cheia is the most idiomatic.

Could you also say tenho a agenda cheia esta semana? Is there a difference?

Yes, you can say both, and both are correct:

minha agenda está cheia esta semana
- Literally: my schedule is full this week.
- Focus on the state of your schedule this week.
tenho a agenda cheia esta semana
- Literally: I have a full schedule this week.
- Focus a little more on you having that full schedule.

In practice, the meaning is almost the same. minha agenda está cheia is slightly more common and neutral in everyday speech.

What does mas mean here, and are there other common ways to say but in Brazilian Portuguese?

mas means but, introducing a contrast:

minha agenda está cheia esta semana, mas no domingo eu posso descansar
= my schedule is full this week, but on Sunday I can rest.

Other common ways to express a similar contrast:

porém – more formal/literary than mas.
só que – very common in speech, more informal:
- minha agenda está cheia esta semana, só que no domingo eu posso descansar.
mas is the standard, most neutral conjunction for but.