Ese cinturón me aprieta un poco la cintura.

Me is an indirect object pronoun here. It shows who is affected by the action.

So in Ese cinturón me aprieta un poco la cintura, the belt is the thing doing the action, and me tells us that it is tight on me / it squeezes me.

A very literal breakdown is:

• Ese cinturón = that belt
• me = to me / on me
• aprieta = squeezes / feels tight
• un poco = a little
• la cintura = the waist

Spanish often uses this structure with body parts:

• Me duele la cabeza. = My head hurts.
• Me lavo las manos. = I wash my hands.

This is a very common Spanish pattern. When talking about body parts, Spanish usually uses:

• an indirect object pronoun like me, te, le
• plus the definite article (la, el, los, las)

So instead of saying my waist, Spanish often says the waist, because me already shows whose waist it is.

That is why:

• me aprieta la cintura is more natural than me aprieta mi cintura

Compare:

• Me duele la espalda. = My back hurts.
• Me corté el dedo. = I cut my finger.
• Me lavo la cara. = I wash my face.

Using mi cintura is not impossible in every context, but here it sounds less natural.

Because the verb is apretar and it is a stem-changing verb.

In many present-tense forms, the e in the stem changes to ie:

• aprieto
• aprietas
• aprieta
• apretamos
• apretáis
• aprietan

So:

• Ese cinturón aprieta = That belt is tight / squeezes

This is the same kind of change you see in verbs like:

• cerrar → cierra
• pensar → piensa
• empezar → empieza

Here apretar means something like:

• to squeeze
• to press
• to be tight on
• to pinch

In this sentence, it means the belt is too tight around the waist or presses against the waist a bit.

So me aprieta is often understood as:

• it feels tight on me
• it squeezes me

This is more specific than simply saying the belt is tight in general.

Because Spanish often puts the indirect object pronoun before the verb, and the body part after it.

So the pattern is:

subject + indirect object pronoun + verb + body part

Here:

• Ese cinturón = subject
• me = indirect object pronoun
• aprieta = verb
• la cintura = direct object / body part affected

This is very normal in Spanish:

• La camisa me aprieta los hombros. = The shirt is tight around my shoulders.
• Los zapatos me aprietan los pies. = The shoes squeeze my feet.

To an English speaker, the order may feel unusual, but in Spanish it is standard.

Yes. That would sound natural too.

If the context already makes it obvious where the belt is tight, Spanish can leave out la cintura:

• Ese cinturón me aprieta un poco.

This means:

• That belt is a bit tight on me.

Adding la cintura makes the sentence more explicit:

• it specifies that the belt is tight around the waist

So both are possible:

• Ese cinturón me aprieta un poco.
• Ese cinturón me aprieta un poco la cintura.

The second one is just a bit more detailed.

Both are possible, but they mean different things.

• este cinturón = this belt
• ese cinturón = that belt
• aquel cinturón = that belt over there / that belt farther away

So ese is used when the speaker is referring to a belt that is not right here with them, or simply one that has already been mentioned.

For a learner, the key contrast is:

• este = this
• ese = that

Un poco means a little / a bit.

Here it softens the verb aprieta:

• me aprieta un poco = it’s a little tight on me

So the sentence does not mean the belt squeezes only a little part of the waist. It means the squeezing/tightness is slight.

Compare:

• Me aprieta mucho. = It’s very tight on me.
• Me aprieta un poco. = It’s a bit tight on me.
• No me aprieta. = It isn’t tight on me.

Yes, in this sentence la cintura means the waist.

That is the normal body-part meaning of cintura.

Since cinturón means belt, the combination makes sense:

• the belt is tight around the waist

This is a useful pair to remember:

• cinturón = belt
• cintura = waist

They look similar because they are related words.

Because cinturón is stressed on the last syllable: cin-tu-RÓN.

In Spanish spelling, words that are stressed on the last syllable usually need a written accent if they end in n, s, or a vowel.

Since cinturón:

• ends in n
• is stressed on the last syllable

it needs the accent mark.

This also helps distinguish the pronunciation clearly:

• cinturón = cin-tu-RÓN

Yes, but it is not exactly the same.

• Ese cinturón me aprieta un poco la cintura focuses on the effect on me: the belt feels tight on my waist.
• Ese cinturón está apretado means That belt is tight or fastened tightly, but it does not emphasize the person affected in the same way.

So:

• Me aprieta = it’s tight on me
• Está apretado = it is tight / done up tightly

If you want to describe your own discomfort, me aprieta is often the more natural choice.

Yes. Spanish often uses apretar this way with things that fit tightly on the body, for example:

• Los zapatos me aprietan. = The shoes are tight on me.
• La camisa me aprieta en los hombros. = The shirt is tight in the shoulders.
• El anillo me aprieta el dedo. = The ring is tight on my finger.

So Ese cinturón me aprieta un poco la cintura fits a very common Spanish pattern: an item of clothing/accessory + me/te/le + aprieta + body part.