Si et trobes amb la cantant després de l'assaig, presenta-me-la, perquè m'agrada molt la seva veu.

Because trobar-se amb is a set expression meaning to meet, to run into, or to come across someone.

• trobar by itself usually means to find
• trobar-se amb means to meet/run into

So:

• trobes les claus = you find the keys
• et trobes amb la cantant = you meet / run into the singer

The et is the 2nd person singular reflexive pronoun, part of the pronominal verb trobar-se.

Yes. Si means if, and this is a very normal real/possible condition.

Structure:

• Si + present indicative
• main clause in imperative, present, future, etc.

Here:

• Si et trobes amb la cantant... = If you meet the singer...
• presenta-me-la = introduce her to me

Catalan does not use the subjunctive after si in this kind of sentence.

Cantant is a noun of common gender: the form stays the same, and the article shows whether it is masculine or feminine.

• el cantant = the male singer
• la cantant = the female singer

So in this sentence, la tells you the singer is female.

Because the definite article el becomes l' before a vowel sound.

• el llibre = the book
• l'assaig = the rehearsal

So després de l'assaig means after the rehearsal.

This is just standard Catalan article contraction/apostrophe spelling.

Because després is normally followed by de before a noun or infinitive.

• després de l'assaig = after the rehearsal
• després de sopar = after eating / after dinner

So després de is the expected pattern here.

It is:

• presenta = introduce (informal singular imperative of presentar)
• me = to me
• la = her

So literally it is something like introduce-to-me-her, which in natural English is introduce her to me.

Catalan often attaches object pronouns to an affirmative imperative:

• dóna'm-ho = give it to me
• explica-li = explain to him/her
• presenta-me-la = introduce her to me

Because when Catalan combines an indirect object pronoun and a direct object pronoun, the usual order is:

• indirect object + direct object

Here:

• me = to me
• la = her

So:

• presenta-me-la = introduce her to me

This is parallel to other combinations like:

• dóna-me'l = give it to me
• porta-nos-en = bring us some

Because in affirmative imperatives, attached pronouns often use the enclitic forms, and em becomes me when attached after the verb.

Compare:

• Em presenta la cantant = he/she introduces the singer to me
• Presenta-me-la = introduce her to me

So:

• before the verb: em
• after an affirmative imperative: me

Catalan normally joins pronouns to an affirmative imperative with hyphens.

So:

• presenta + me + la → presenta-me-la

This is standard spelling with attached pronouns after imperatives, infinitives, and gerunds in many cases.

Because agradar works differently from English to like.

Catalan structure is more like:

• something is pleasing to someone

So:

• m'agrada la seva veu literally = her voice pleases me
• natural English = I really like her voice

Here:

• m' = to me
• agrada = pleases / is pleasing
• la seva veu = her voice

This is one of the most important differences for English speakers learning Catalan.

Because the subject of agradar here is la seva veu, which is singular.

• la seva veu = her voice
• therefore agrada = singular

Compare:

• M'agrada la seva veu = I like her voice
• M'agraden les seves cançons = I like her songs

So the verb agrees with the thing liked, not with the person who likes it.

Seva is a possessive meaning his, her, its, or their, depending on context. It agrees with the noun possessed, not with the owner.

Here:

• veu is feminine singular
• so the possessive must be seva

Forms:

• el seu llibre = his/her/their book
• la seva veu = his/her/their voice
• els seus amics = his/her/their friends
• les seves cançons = his/her/their songs

In this sentence, context tells us seva refers to the singer’s voice.

Because perquè as one word means because.

• perquè = because
• per què = why / for what reason

So here:

• ..., perquè m'agrada molt la seva veu. = ..., because I really like her voice.

This is a very common distinction in Catalan spelling.

Molt means very much here.

• m'agrada molt = I like ... a lot / very much

It intensifies the verb phrase, not the noun.

Compare:

• m'agrada molt = I like it very much
• una veu molt bonica = a very beautiful voice

So molt can modify different things depending on position and structure.

Yes. Presenta is the tu imperative, so it is informal singular.

If you were addressing someone formally (vostè), you would say:

• Si es troba amb la cantant després de l'assaig, presenti-me-la...

Main changes:

• et trobes → es troba
• presenta → presenti

So the original sentence is clearly aimed at someone you address as tu.

Yes. Trobar-se amb often suggests meeting someone, and very often it can mean running into someone, whether planned or unplanned. Context decides.

In this sentence, it sounds like:

• If you happen to meet the singer after the rehearsal, introduce her to me

So it may well imply a chance encounter rather than a scheduled meeting.