Eu gosto das músicas delas.

In Portuguese, the verb gostar almost always needs the preposition de before the thing you like.

• Eu gosto. = I like (in general, but you’re not saying what you like)
• Eu gosto de música. = I like music.
• Eu gosto das músicas delas. = I like their songs.

So in your sentence, the underlying structure is:

• Eu gosto de as músicas delas. → this contracts to Eu gosto das músicas delas.

Das is a contraction of:

• de (from the verb gostar de)
  +
• as (the feminine plural definite article, “the”)

So:

• de + as = das

Grammatically, the sentence is:

• Eu gosto de as músicas delas. → Eu gosto das músicas delas.

English doesn’t show this contraction because it doesn’t use articles and prepositions in the same way, but literally it’s something like:

• I like *of the songs of them. → *I like their songs.

Delas is a contraction of de + elas and agrees with the people who own the songs:

• dele = of him
• dela = of her
• deles = of them (masculine or mixed group)
• delas = of them (all-female group)

So delas tells you:

1. There is more than one owner (plural).
2. All the owners are female.

If the songs belonged to a group of men, you’d say:

• Eu gosto das músicas deles.

No. In standard Portuguese, de + personal pronoun must contract:

• de + ele → dele
• de + ela → dela
• de + eles → deles
• de + elas → delas

So:

• ❌ as músicas de elas
• ✅ as músicas delas

Both can translate as “their songs”, but there are nuances:

1. as músicas delas

   • Literally: the songs of them (fem.)
   • Very clear: the owners are a female group.
   • Avoids the ambiguity of sua/suas, which can mean his/her/your/their.

2. as suas músicas

   • Means your songs or his/her/their songs, depending on context.
   • In European Portuguese, possessives usually take the article: as suas músicas.
   • Often used when talking directly to someone:
     
     • Eu gosto das tuas músicas. = I like your songs (informal “you”).
     • Eu gosto das suas músicas. = I like your songs (formal “you”).

Using delas makes it explicit that the songs belong to them (a group of women), not to you or to him/her.

Yes, both are possible, but they’re not identical:

• Eu gosto das músicas delas.

  • I like their songs.
  • Emphasises individual songs; you’re talking about several specific tracks.

• Eu gosto da música delas.

  • Literally: I like the music of them.
  • More about their music in general or their musical style as a whole.

So músicas focuses on separate pieces; música focuses on the overall music.

They talk about different levels of specificity:

• Gosto de música.

  • No article.
  • Means I like music (in general), as a concept or activity.

• Gosto das músicas delas.

  • Has das (= de + as).
  • Means I like *the songs of theirs specifically.*
  • You’re not talking about music in general; you’re talking about particular songs by those people.

Article present → more specific; article absent → more general.

You can omit Eu:

• Eu gosto das músicas delas.
• Gosto das músicas delas.

Both are correct. Portuguese is a pro-drop language, so subject pronouns are often dropped because the verb ending (-o in gosto) already shows the subject is eu (I).

You typically include Eu if you want to:

• Emphasise the subject: Eu gosto, mas ele não gosta.
• Avoid ambiguity in more complex sentences.

No. That’s a direct transfer from English and it’s incorrect in Portuguese.

In Portuguese:

• gostar does not take a direct object.
• It takes de + noun instead.

So:

• ❌ Eu gosto as músicas delas.
• ✅ Eu gosto das músicas delas. (literally: I like *of the songs of them.*)

The natural order is:

• as músicas delas (noun + delas)

You can’t move delas in front of the noun:

• ❌ as delas músicas
• ❌ delas as músicas (this sounds very odd in modern Portuguese)

For possession with de, the pattern is:

• [article] + [noun] + [dele/dela/deles/delas]
  e.g. o carro dele, as ideias delas, as músicas delas.

Just change the last word to match the owners:

• One woman:
  • Eu gosto das músicas dela. = I like her songs.
• One man:
  • Eu gosto das músicas dele. = I like his songs.
• Mixed group or group of men:
  • Eu gosto das músicas deles. = I like their songs. (masc./mixed)
• Group of women:
  • Eu gosto das músicas delas. = I like their songs. (fem. only)

The rest of the sentence stays the same.

Structurally, Eu gosto das músicas delas. is correct and natural in both European and Brazilian Portuguese.

Minor differences:

• Pronunciation will differ (especially vowels and the s sounds).
• In both varieties, people also often say Eu gosto da música delas when they mean I like their music (in general).

But grammatically and in terms of word choice, the sentence works the same in Portugal and Brazil.

You can break it down like this:

• Eu – I (subject pronoun)
• gosto – like (1st person singular, present tense of gostar)
• de – required preposition after gostar
• as – the (feminine plural article, agrees with músicas)
• músicas – songs (feminine plural noun)
• delas – of them (feminine plural), shows who the songs belong to

Mechanically:

1. Start: Eu gosto de… (I like…)
2. Add the noun phrase: as músicas delas (their songs / the songs of them).
3. Contract de + as → das:

Eu gosto de as músicas delas. → Eu gosto das músicas delas.