En el mercadillo compré un souvenir pequeño para mi profesora y otro para mi vecina.

Mercadillo usually means a street market, flea market, or small market with stalls. It often suggests a temporary or open-air market.

Mercado is the more general word for market, and it can also mean a regular market building or food market.

So en el mercadillo gives a slightly more specific image than just en el mercado.

Because en means in / at, and here the sentence says where the action happened: the speaker bought it at the market.

• En el mercadillo = at/in the market
• Al mercadillo = to the market

If you said Fui al mercadillo, that would mean I went to the market.
But in this sentence, the important idea is where the buying took place, so en is the natural choice.

Compré is the first person singular form of the preterite tense of comprar:

• yo compré = I bought

The accent matters because it distinguishes it from compre, which can be a different form, such as the present subjunctive.

So:

• compré = I bought
• compre = a different grammatical form, not the one used here

It is the preterite tense, used for a completed action in the past.

Here, the speaker is talking about one finished action:

• I bought a small souvenir...

That is why the preterite is used instead of the imperfect.

Yes, souvenir is used in Spanish too, especially in everyday speech and in tourist contexts. It is a borrowed word.

You may also hear:

• recuerdo = souvenir / keepsake

In many situations, both work, but souvenir is very common and sounds natural.

In this sentence, souvenir is treated as masculine, which is why it takes:

• un
• pequeño
• otro

So the grammar shows its gender:

• un souvenir pequeño
• otro = another one referring to the same masculine noun

Loanwords in Spanish have to behave like nouns in the language, so they get a grammatical gender. Here, it is masculine.

In Spanish, descriptive adjectives usually come after the noun.

So:

• un souvenir pequeño = a small souvenir

This is the normal word order.
If an adjective comes before the noun in Spanish, it often adds a different nuance or sounds more literary or subjective. Here, the basic descriptive order is the expected one.

Spanish often avoids repeating a noun if it is already clear. That is what otro is doing here.

• un souvenir pequeño para mi profesora y otro para mi vecina

The second part means:

• and another one for my neighbour

The noun souvenir is understood, so it does not need to be repeated.

Otro means another or another one.

In this sentence, it stands for:

• otro souvenir

So the full idea is:

• I bought a small souvenir for my teacher and another one for my neighbour.

Because it refers back to souvenir, it is masculine singular:

• otro

If the noun were feminine, you would use otra.

Para is used here to mean for, showing the intended recipient.

• para mi profesora = for my teacher
• para mi vecina = for my neighbour

This is the normal preposition when something is intended for someone.

Because para and por are not interchangeable.

Here, para is correct because it marks the recipient or intended destination of the gift.

• Compré un souvenir para mi profesora = I bought a souvenir for my teacher

Using por here would usually sound wrong in standard Spanish for this meaning.

A very rough guide:

• para = for, intended for, in order to
• por = because of, through, by, around, in exchange for, etc.

In Spanish, possessives like mi, tu, su, nuestro, etc. normally replace the article.

So you say:

• mi profesora
• mi vecina

not:

• la mi profesora
• la mi vecina

That kind of structure is not normal in modern standard Spanish.

They are feminine because they refer to female people.

• profesora = female teacher
• vecina = female neighbour

If they were male, you would have:

• mi profesor
• mi vecino

This also helps explain why the sentence says mi profesora and mi vecina.

Yes. Spanish word order is flexible as long as the meaning stays clear.

For example, you could also say:

• Compré en el mercadillo un souvenir pequeño para mi profesora y otro para mi vecina.

That still sounds natural.

The original sentence begins with En el mercadillo, which puts a little more focus on the place:

• At the market, I bought...

Usually, yes, many listeners will naturally understand otro as another souvenir of the same kind, especially in this context.

So the sentence often suggests:

• one small souvenir for the teacher
• another small souvenir for the neighbour

However, strictly speaking, otro directly replaces souvenir, and the adjective is not repeated. If the speaker wanted to make it fully explicit, they could say:

• ...y otro pequeño para mi vecina.

That would remove any possible doubt.