Basisten spelar ackordet igen.

Because -en is the definite singular ending for many common-gender Swedish nouns.

• basist = bassist
• basisten = the bassist

So Swedish often puts the equivalent of the at the end of the noun instead of using a separate word before it.

In Swedish, the definite article is usually attached to the noun as a suffix.

So instead of saying something like the bassist with a separate article, Swedish says:

• basisten = the bassist
• ackordet = the chord

This is one of the biggest differences from English noun structure.

Because ackordet is the definite form of ackord.

• ett ackord = a chord
• ackordet = the chord

Ackord is a neuter noun in Swedish, so its definite singular ending is -et.

Spelar is the present tense of the verb spela.

• spela = to play
• spelar = play / is playing

In Swedish, verbs do not change according to the subject the way they do in English. So the same form is used with I, you, he/she/it, we, and they.

For example:

• jag spelar = I play
• du spelar = you play
• basisten spelar = the bassist plays

It can mean either one, depending on context.

Swedish present tense often covers both:

• plays
• is playing

So Basisten spelar ackordet igen could mean either:

• The bassist plays the chord again
• The bassist is playing the chord again

Usually the wider context tells you which is more natural.

Igen means again.

In this sentence, it comes at the end because that is a very natural position for it in Swedish:

• Basisten spelar ackordet igen.

Swedish adverbs like igen often come after the object. English can also do this: plays the chord again.

You may also see word-order variation in other contexts, but this placement is very common and natural.

Yes: it follows normal Swedish main clause word order, where the finite verb usually comes in the second position.

Here the sentence is:

• Basisten = subject
• spelar = finite verb
• ackordet = object
• igen = adverb

So the pattern is:

Subject + verb + object + adverb

This is very standard Swedish word order.

In a yes/no question, Swedish usually puts the verb before the subject:

• Spelar basisten ackordet igen?
  = Is the bassist playing the chord again? / Does the bassist play the chord again?

So the statement:

• Basisten spelar ackordet igen.

becomes the question:

• Spelar basisten ackordet igen?

A rough pronunciation guide for an English speaker is:

• basisten ≈ bah-SEE-sten
• spelar ≈ SPAY-lar
• ackordet ≈ ah-KOR-det
• igen ≈ ee-YEN

A few helpful notes:

• sj-type sounds do not appear here, so this sentence is relatively straightforward.
• The g in igen is not pronounced like hard English g in go.
• Swedish vowel length and stress matter, so listening to native audio is very helpful.

Yes. Basist means a bass player, but exactly what kind depends on context.

It could refer to someone playing:

• bass guitar
• double bass
• another bass instrument

So basisten simply means the bass player / the bassist, without specifying the exact instrument unless the context makes it clear.