De vegades no puc dormir perquè hi ha soroll al carrer.

De vegades means sometimes.

Literally, vegades means times/occasions, so the expression is like saying at times.

A very common alternative is A vegades, which also means sometimes. In everyday Catalan, both are widely used.

Catalan often leaves out subject pronouns when the verb already makes the subject clear.

• puc = I can
• so (jo) no puc dormir = I can’t sleep

You could say Jo no puc dormir, but it usually sounds more emphatic, as if you are stressing I.

Puc is the 1st person singular present form of the verb poder (to be able to / can).

Present tense of poder:

• jo puc = I can
• tu pots = you can
• ell/ella pot = he/she can
• nosaltres podem = we can
• vosaltres podeu = you all can
• ells/elles poden = they can

So no puc dormir means I can’t sleep.

After poder, Catalan uses the infinitive directly, with no extra preposition.

• puc dormir = I can sleep
• puc venir = I can come
• puc menjar = I can eat

So no puc dormir is the normal structure:

• no = not
• puc = I can
• dormir = sleep

In Catalan, standard negation is formed by putting no before the conjugated verb.

• puc dormir = I can sleep
• no puc dormir = I can’t sleep

This is the normal placement. It works much like French ne...pas in position before the verb, but in Catalan the basic negative word is simply no.

Here perquè means because.

So:

• No puc dormir perquè hi ha soroll al carrer
  = I can’t sleep because there is noise in the street

A common learner question is the difference between:

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

Examples:

• No vinc perquè estic cansat. = I’m not coming because I’m tired.
• Per què no véns? = Why aren’t you coming?

Hi ha means there is or there are.

It is the Catalan way to express existence:

• Hi ha un llibre a la taula. = There is a book on the table.
• Hi ha cotxes al carrer. = There are cars in the street.

In your sentence:

• hi ha soroll = there is noise

In hi ha, the word hi is part of the fixed existential expression meaning there is / there are.

For learners, it is best to memorize hi ha as a single unit:

• hi ha = there is / there are

Even though hi can also function elsewhere as a locative pronoun (there, in it, at it, depending on context), in this expression you should mainly think of hi ha as the standard Catalan equivalent of English there is / there are.

Soroll here is being used in a general, uncountable sense: noise.

So:

• hi ha soroll = there is noise

If you say hi ha un soroll, it sounds more like there is a noise / a particular noise, often a specific sound someone notices.

Compare:

• Hi ha soroll al carrer. = There is noise in the street.
• Hi ha un soroll estrany al carrer. = There is a strange noise in the street.

Al carrer means in the street or on the street, depending on how English would express it in context.

It comes from:

• a = to / at / in / on
• el = the

These contract:

• a + el = al

So:

• al carrer = in/on the street

This contraction is very common in Catalan.

Yes, al is normally the contraction of a + el.

Examples:

• al carrer = a + el carrer
• al cotxe = a + el cotxe
• al parc = a + el parc

Similarly:

• del = de + el

Examples:

• del carrer = of/from the street
• del llibre = of the book

The sentence follows a very natural Catalan order:

• De vegades = sometimes
• no puc dormir = I can’t sleep
• perquè = because
• hi ha soroll = there is noise
• al carrer = in the street

So the structure is basically:

Sometimes + I can’t sleep + because + there is noise + in the street

This is quite parallel to English, which makes the sentence relatively straightforward for learners.

Yes. A vegades and De vegades both mean sometimes and are both common.

So these both work:

• De vegades no puc dormir perquè hi ha soroll al carrer.
• A vegades no puc dormir perquè hi ha soroll al carrer.

The meaning is essentially the same.

A simple approximate pronunciation for an English speaker is:

duh vuh-GAH-duhs no pook door-MEER per-KEH ee AH soo-ROY al kuh-REHR

A few useful notes:

• puc has a u like oo in food
• perquè is stressed on the last syllable: per-QUÈ
• soroll has a ll sound that varies by accent, often like a soft y sound
• carrer is stressed on the last syllable: ca-RRER

Exact pronunciation varies somewhat by dialect, but this will help you recognize and say the sentence.