Στο γυμναστήριο έχω πάντα αποσμητικό και μικρό πιστολάκι, γιατί δεν θέλω να γυρίζω σπίτι με βρεγμένα μαλλιά.

Στο is the contracted form of σε + το.

• σε = in / at / to
• το = the for a neuter noun

So:

• σε το γυμναστήριο → στο γυμναστήριο

This contraction is completely standard in modern Greek. You will very often see:

• στο = σε το
• στη = σε τη(ν)
• στον = σε τον

It can mean either, depending on context. In modern Greek, σε + accusative is used for both location and movement.

Here, because the verb is έχω (I have / I keep), the meaning is clearly at the gym:

• Στο γυμναστήριο έχω... = At the gym I have / keep...

If the sentence had a motion verb, the same phrase could mean to the gym.

Greek word order is more flexible than English word order. The speaker puts Στο γυμναστήριο first to set the scene or topic:

• Στο γυμναστήριο = At the gym
• then έχω πάντα... = I always have...

This sounds natural and helps highlight the place first. Greek often moves time/place expressions to the front for emphasis or topic-setting.

Greek often leaves out the indefinite article where English would use a/an, especially in lists or when talking about things in a general, non-emphatic way.

So:

• έχω πάντα αποσμητικό και μικρό πιστολάκι
  = I always have deodorant and a small hair dryer

You could also say:

• έχω πάντα ένα αποσμητικό και ένα μικρό πιστολάκι

That would be more explicit, a bit more like I always have a deodorant and a small hair dryer. But in natural Greek, omitting ένα here is very common.

Αποσμητικό means deodorant.

It is a neuter noun:

• το αποσμητικό = the deodorant

In this sentence it appears without the article, which is normal, as mentioned above.

Yes. Πιστολάκι literally looks like little gun, because it comes from πιστόλι (gun) plus the diminutive ending -άκι.

But in everyday Greek, πιστολάκι commonly means hair dryer / blow dryer.

So:

• μικρό πιστολάκι = a small hair dryer

Even though the literal image is funny, this is a normal everyday word.

Because adjectives in Greek must agree with the noun in gender, number, and case.

Πιστολάκι is:

• singular
• neuter

So the adjective must also be singular neuter:

• μικρό πιστολάκι

Compare:

• μικρός άντρας = small man
• μικρή τσάντα = small bag
• μικρό πιστολάκι = small hair dryer

Yes, γιατί can mean both because and why.

Here it means because, since it introduces a reason:

• ..., γιατί δεν θέλω... = ..., because I don’t want...

When it is used in a question, it means why:

• Γιατί έφυγες; = Why did you leave?

So the meaning depends on context and punctuation.

After θέλω (I want), Greek normally uses να + verb.

So:

• θέλω να πάω = I want to go
• θέλω να φύγω = I want to leave
• δεν θέλω να γυρίζω = I don’t want to return / go back

The particle να is a basic part of modern Greek grammar and is used where English often uses the infinitive (to go, to return, etc.). Since modern Greek does not have an English-style infinitive, να + verb does that job in many cases.

It can mean turn, but it also very often means return, go back, or come back, depending on context.

So here:

• δεν θέλω να γυρίζω σπίτι = I don’t want to go back home / return home

This is a very common everyday use of γυρίζω.

This is a very important Greek aspect difference.

• να γυρίζω = present subjunctive, showing an ongoing, repeated, or habitual action
• να γυρίσω = aorist subjunctive, showing a single, whole, completed action

In this sentence, the speaker is talking about a general habit or repeated situation after the gym, so να γυρίζω fits well:

• δεν θέλω να γυρίζω σπίτι με βρεγμένα μαλλιά
  = I don’t want to be going home / to go home habitually with wet hair

If you said να γυρίσω, it would sound more like a single occasion:

• I don’t want to go back home with wet hair this time

Both are grammatically possible in the right context, but να γυρίζω is the more natural choice for a repeated/general situation.

Because σπίτι can function in an idiomatic way meaning home.

So:

• πάω σπίτι = I’m going home
• γυρίζω σπίτι = I’m returning home
• μένω σπίτι = I’m staying home

You can also say στο σπίτι in other contexts, but when Greek means home as a destination or general location, bare σπίτι is very common.

Here με means with, and the phrase describes the condition in which the person would be going home:

• με βρεγμένα μαλλιά = with wet hair

This is a very common Greek structure:

• με κλειστά μάτια = with closed eyes
• με βρώμικα παπούτσια = with dirty shoes
• με βρεγμένα μαλλιά = with wet hair

So the idea is: I don’t want to go home while having wet hair / with my hair wet.

In Greek, μαλλιά is normally used in the plural when talking about someone’s hair in general.

• τα μαλλιά μου = my hair
• literally: my hairs

So:

• βρεγμένα μαλλιά = wet hair

Because μαλλιά is plural neuter, the adjective must also be plural neuter:

• βρεγμένα

That is why you do not see βρεγμένο μαλλί here. That would not be the normal way to talk about someone’s hair.

Πάντα means always.

It modifies έχω:

• έχω πάντα = I always have

So the speaker means this is a regular habit, not something occasional:

• At the gym, I always have deodorant and a small hair dryer...

Greek adverbs like πάντα can move around somewhat, but this position is very natural.

Yes. Έχω literally means I have, but in context it can imply I keep, I carry, or I make sure I have with me.

So depending on context, this sentence could suggest:

• I keep these things at the gym
• I always have these things with me at the gym
• I make sure to bring these things to the gym

Greek often lets context supply that nuance rather than choosing a more specific verb.