Mi abuela me regaló un chaleco de lana muy cómodo para el invierno.

Me means to me here. In Spanish, with verbs like regalar (to give as a gift), you often use an indirect object pronoun to show who received the gift.

So in this sentence:

• Mi abuela = my grandmother
• me = to me
• regaló = gave as a gift
• un chaleco = a vest / waistcoat

A useful pattern is:

regalar algo a alguien = to give something to someone as a gift

So this sentence is literally structured like:

My grandmother gave me a wool vest as a gift...

Regaló is the preterite form of regalar for él/ella/usted:

• yo regalé
• tú regalaste
• él/ella/usted regaló

It means gave or gave as a gift.

The accent mark is important because it shows the stress and also distinguishes it from regalo:

• regalo = I give / gift
• regaló = he/she gave

So Mi abuela me regaló... means My grandmother gave me..., not My grandmother gives me...

In modern Spanish, possessive adjectives like mi, tu, su, nuestro normally come instead of the article, not with it.

So you say:

• mi abuela = my grandmother
• tu casa = your house
• su libro = his/her/their book

Not:

• la mi abuela ❌

That structure is not standard modern Spanish.

These are two different words:

• mi (no accent) = my
• mí (with accent) = me after a preposition, as in para mí (for me)

In this sentence, mi abuela means my grandmother, so it must be mi without an accent.

Compare:

• Mi abuela = my grandmother
• para mí = for me

Chaleco is a masculine noun. In Spain, it usually means vest or sometimes waistcoat, depending on context.

Because it is masculine singular, it takes:

• un chaleco = a vest

Not:

• una chaleco ❌

You can often tell from the ending -o that a noun is masculine, though there are exceptions in Spanish.

De lana means made of wool or woolen.

Spanish very often uses de + material to describe what something is made of:

• una mesa de madera = a wooden table
• una camisa de algodón = a cotton shirt
• un chaleco de lana = a wool vest

You do not usually use the article here:

• de lana ✅
• de la lana ❌ in this context

De la lana would sound like of the wool, referring to some specific wool already mentioned.

Because cómodo describes chaleco, not abuela.

In Spanish, adjectives must agree with the noun they describe in gender and number:

• chaleco = masculine singular
• so: cómodo = masculine singular

If the noun were feminine, it would change:

• una chaqueta muy cómoda = a very comfortable jacket

So in your sentence:

• un chaleco... muy cómodo = a very comfortable vest

Because muy is used to modify adjectives and adverbs, while mucho usually means much/many/a lot.

Here, cómodo is an adjective, so you need:

• muy cómodo = very comfortable

Compare:

• muy cómodo = very comfortable
• mucho frío = a lot of cold / very cold weather sense
• muchos libros = many books

So:

• muy cómodo ✅
• mucho cómodo ❌

Para often expresses purpose, intended use, or what something is for.

So para el invierno means:

• for the winter
• for use in winter
• suitable for winter

It tells you the vest is intended to be worn in that season.

This is very natural in Spanish:

• ropa para el verano = clothes for summer
• botas para la lluvia = boots for the rain
• un abrigo para el invierno = a coat for winter

Yes, but the meaning changes slightly.

• para el invierno = for winter, emphasizing purpose or suitability
• en invierno = in winter, emphasizing the time when something happens or is used

So:

• un chaleco de lana muy cómodo para el invierno = a very comfortable wool vest for winter
• un chaleco de lana muy cómodo en invierno = a very comfortable wool vest in winter

The first one is more natural if you mean the vest is meant for that season.

Because me already tells us to me.

Spanish normally uses the unstressed indirect object pronoun before the verb:

• me regaló = gave me

You could add a mí for emphasis or contrast:

• Mi abuela me regaló a mí un chaleco...

But that would only be used if you wanted to stress me specifically, for example in contrast with someone else.

In a normal sentence, me by itself is enough.

Because object pronouns like me, te, lo, la, le, nos usually go before a conjugated verb.

So:

• me regaló = she gave me

This is standard Spanish word order with pronouns.

Compare:

• Me llamó = she called me
• Te escribió = he wrote to you
• Nos ayudaron = they helped us

Pronouns can go after the verb in some cases, such as with infinitives, gerunds, and affirmative commands, but not here.

A simple breakdown is:

• Mi abuela = subject
• me = indirect object pronoun
• regaló = verb
• un chaleco de lana muy cómodo = direct object, with description
• para el invierno = phrase showing purpose/use

So the sentence follows this pattern:

[Subject] + [indirect object pronoun] + [verb] + [thing given] + [extra description]

More specifically:

Mi abuela
me regaló
un chaleco
de lana
muy cómodo
para el invierno

This is a very common and natural Spanish sentence structure.