A mercearia da esquina deve ter bananas, peras e pêssegos mais baratos.

Deve ter is dever + infinitive. In sentences like this, it often expresses expectation or probability, so it can mean should have or probably has.

Depending on context, deve ter can also mean something closer to must have or ought to have, but here it most naturally sounds like an expectation about what the shop is likely to stock or offer.

Portuguese often uses the definite article where English may not. A mercearia means the grocery shop and refers to a specific, identifiable shop.

Leaving out the article would sound unnatural in a normal full sentence.

In Portugal, mercearia usually means a small grocery shop, neighborhood food shop, or corner store. It is not usually the same as a large supermercado.

So a mercearia da esquina strongly suggests the corner shop rather than a big supermarket.

Because da is the contraction of de + a.

So:

• de + a = da

Literally, a mercearia da esquina is something like the grocery shop of the corner, but in natural English it means the grocery shop on the corner or the corner shop.

Yes, but the nuance is a bit different.

• a mercearia da esquina = the corner shop, identifying which shop you mean
• a mercearia na esquina = the shop on the corner, focusing more directly on its location

Both are possible, but da esquina is especially common when you mean the familiar local corner shop.

After ter, Portuguese often leaves out articles when talking about things in a general, non-specific way.

So:

• ter bananas = to have bananas
• ter as bananas = to have the bananas, meaning specific bananas already known from context

Here, the sentence is talking about fruit in general, so no articles are needed.

Because baratos describes all three nouns together: bananas, peras e pêssegos.

Two of those nouns are feminine plural:

• bananas
• peras

But pêssegos is masculine plural. In Portuguese, when an adjective refers to a mixed-gender plural group, the default agreement is masculine plural.

So:

• all feminine nouns together -> baratas
• mixed group -> baratos

In normal reading, it describes all three fruits.

Because mais baratos comes after the whole list, it naturally applies to bananas, peras e pêssegos together.

If the speaker wanted to make different prices or descriptions for different fruits clearer, they would normally restructure the sentence.

Because adjectives usually come after the noun in Portuguese.

That is also true for comparative forms like mais barato / mais baratos.

So Portuguese naturally says:

• bananas mais baratas
• pêssegos mais baratos

Putting the adjective before the noun would sound unnatural here.

That is normal. Mais baratos is comparative, but Portuguese often leaves the comparison unstated when it is understood from context.

It could mean:

• cheaper than in another shop
• cheaper than somewhere else nearby
• cheaper than expected
• cheaper than before

The listener is expected to infer the comparison from the situation.

Because mais baratos means cheaper, while baratos just means cheap.

So the sentence is not only saying that the fruit is low-priced. It is saying that it is lower-priced in comparison with something else, even if that comparison is left implicit.

The accent in pêssegos helps show the stressed syllable and vowel quality. The stress falls on the first syllable: PÊS-se-gos.

This is useful because Portuguese spelling often marks stress when it does not follow the most basic default pattern. For learners, the important point is that the first syllable is stressed.