Compro delle ciliegie al mercato per il dessert.

In Italian, the subject pronoun is often omitted because the verb ending already shows who is doing the action.

• compro = I buy / I am buying
• The -o ending tells you the subject is io

So Compro delle ciliegie... is perfectly natural.
You can say Io compro... too, but it usually adds emphasis, such as I’m the one buying them.

Compro is the present indicative of comprare.

It can correspond to different English present meanings depending on context:

• I buy
• I am buying
• sometimes even I’m buying in the sense of a planned action

In Compro delle ciliegie al mercato per il dessert, it could mean:

• I buy some cherries at the market for dessert
  or
• I’m buying some cherries at the market for dessert

Italian uses the simple present more broadly than English often does.

Here delle means some.

So:

• delle ciliegie = some cherries

Grammatically, delle is a partitive article, used when talking about an indefinite quantity of something.

It comes from:

• di + le = delle

Even though it literally looks like of the, in sentences like this it usually just means some.

Both are possible, but they are slightly different in feel.

• Compro delle ciliegie = I’m buying some cherries
• Compro ciliegie = I buy cherries / I’m buying cherries, more general or less specific sounding

Using delle makes the quantity feel more natural and concrete, as if you mean some cherries rather than cherries in a broad sense.

Good question. The singular is:

• ciliegia = cherry

The plural is:

• ciliegie = cherries

With nouns ending in -cia or -gia, the plural can be tricky. A common guideline is:

• if the i is stressed, it stays
• if the c or g comes after a vowel, the i often stays
• if it comes after a consonant, the i often drops

Since ciliegia has -gia after a vowel, the plural is normally ciliegie.

Al mercato means at the market.

It is formed from:

• a = at / to
• il mercato = the market

These combine into:

• a + il = al

So:

• al mercato = at the market
  or sometimes to the market, depending on context

Here, it most naturally means the place where the buying happens: at the market.

Both can exist, but they are not used in exactly the same way.

• al mercato usually means at the market, in the general sense of going there, shopping there, being there
• nel mercato literally means in the market, emphasizing being inside it physically

For ordinary shopping contexts, al mercato is the natural choice.

Per il dessert means for dessert.

It explains the purpose of buying the cherries:

• per = for
• il dessert = the dessert

So the sentence means the cherries are intended to be eaten as dessert, or used for dessert.

In Italian, nouns often use an article where English might not focus on one.

• il dessert = the dessert

In expressions like per il dessert, the article is very natural. It often refers to the dessert course in a general, understood sense.

Italian commonly uses definite articles more than English does.

Yes, dessert is used in Italian, especially in modern everyday language. It is a loanword from French, but it is very common.

You may also hear:

• dolce = dessert / sweet

So you could also say:

• Compro delle ciliegie al mercato per il dolce.

That sounds natural too, though dessert can sound slightly more modern or international depending on context.

Yes. The Italian present can describe:

• a habitual action
• a current action
• a near-future action, depending on context

So Compro delle ciliegie al mercato per il dessert could mean:

• I buy some cherries at the market for dessert as a regular thing
• I’m buying some cherries at the market for dessert right now / today

Context tells you which meaning is intended.

Yes. That would emphasize that the action is in progress right now.

• Compro delle ciliegie... = I buy / I’m buying some cherries...
• Sto comprando delle ciliegie... = I am buying some cherries right now

Italian often prefers the simple present where English would use am buying, so compro is already very natural.

The order is quite natural in Italian:

• Compro = verb
• delle ciliegie = what you buy
• al mercato = where
• per il dessert = purpose

So it is basically:

I buy some cherries at the market for dessert.

Italian word order is flexible, but this version is straightforward and neutral. You could move parts around for emphasis, for example:

• Al mercato compro delle ciliegie per il dessert.

That puts more emphasis on at the market.

Yes, but the meaning changes.

• delle ciliegie = some cherries
• le ciliegie = the cherries

Use le ciliegie if you mean specific cherries already known in the conversation:

• Compro le ciliegie al mercato per il dessert.
  = I’m buying the cherries at the market for dessert.

Use delle ciliegie when they are indefinite: just some cherries.

The dictionary form is comprare, which means to buy.

This is a regular -are verb:

• io compro = I buy
• tu compri = you buy
• lui/lei compra = he/she buys
• noi compriamo = we buy
• voi comprate = you all buy
• loro comprano = they buy

So compro is simply the io form of comprare.