Learn Hardcore Greek: Μια μικρή μείωση στον χρόνο που περνάω στο κινητό βοηθάει πολύ τη συγκέντρωσή μου. - A small reduction in the time I spend on my phone helps my concentration a lot.

So you get: Μια μικρή μείωση.
If the noun were neuter (e.g. ένα μικρό λάθος – a small mistake), you would use ένα μικρό. Here the gender is fixed by the noun μείωση.

What exactly does μείωση mean, and why do we use it here?

Μείωση means reduction, decrease. It’s the noun that comes from the verb μειώνω (to reduce).

In this sentence, μια μικρή μείωση means a small reduction – i.e. a slightly smaller amount of time. It’s a bit more formal than just saying να περνάω λίγο λιγότερο χρόνο (to spend a bit less time), but perfectly natural.

Why is it στον χρόνο and not στο χρόνο or something else?

Στον is the contraction of σε + τον (to/at + the, masculine accusative):

σε + τον χρόνο → στον χρόνο

Χρόνος is masculine, and in this sentence it is in the accusative singular (τον χρόνο), so you need στον.

In everyday speech, many people drop the -ν and say στο χρόνο, but grammatically στον χρόνο is the full form.

Why is χρόνο singular here? In English I might say “amount of time” or think of many minutes/hours.

Greek often uses χρόνος in the singular to mean time in general or a quantity of time, which is conceptually uncountable.

So μείωση στον χρόνο here is like saying a reduction in (the amount of) time.
Using a plural like στους χρόνους would sound wrong in this context; it’s used in different meanings (e.g. grammatical tenses).

What is the role of που in τον χρόνο που περνάω στο κινητό?

Here που is a relative pronoun, roughly meaning that / which:

τον χρόνο που περνάω στο κινητό
→ the time that I spend on my phone

In more formal Greek you could use τον χρόνο τον οποίο περνάω στο κινητό, but που is by far the most common everyday choice.

What tense and person is περνάω, and is there a difference between περνάω and περνώ?

Περνάω is 1st person singular, present tense, active voice: I pass / I spend (time).

There are two forms:

περνάω (more common in everyday speech)
περνώ (a bit more formal/literary, but also correct)

They mean the same thing in this context. So τον χρόνο που περνάω στο κινητό = the time I spend on my phone.

Why is it στο κινητό and not στο τηλέφωνο?

In modern Greek, το κινητό is a shortening of το κινητό τηλέφωνο and is the normal way to say mobile phone / cell phone.

στο κινητό literally = on the mobile (phone)
In English we usually say on my phone, but Greek often omits the possessive when it’s obvious.

You could say στο κινητό μου (on my phone), but it’s not necessary; context makes it clear.

Why is it βοηθάει? Could it also be βοηθά?

Βοηθάει is 3rd person singular, present tense of βοηθάω: he/she/it helps.

The subject is Μια μικρή μείωση… (a small reduction), so the verb must agree in 3rd person singular: βοηθάει.

There are two parallel forms:

βοηθάει
βοηθά

Both are correct and mean the same. Βοηθά is slightly shorter and often preferred in writing, but both are very common.

What is πολύ doing in βοηθάει πολύ τη συγκέντρωσή μου?

Here πολύ is an adverb meaning a lot / very much and it modifies the verb βοηθάει:

βοηθάει πολύ = helps a lot / really helps

Don’t confuse this with πολλή (with double λ and feminine ending), which is an adjective:

πολλή βοήθεια = a lot of help (noun)
βοηθάει πολύ = helps a lot (adverb)

Why is it τη συγκέντρωσή μου and not just συγκέντρωση μου?

Greek almost always uses the definite article with a possessed noun:

η συγκέντρωσή μου = my concentration
in the accusative: τη συγκέντρωσή μου

So βοηθάει τη συγκέντρωσή μου = it helps my concentration.
Omitting the article (βοηθάει συγκέντρωση μου) sounds ungrammatical.

Why does συγκέντρωση become συγκέντρωσή (with the accent on the last syllable) before μου?

The base word is η συγκέντρωση (accent on the -γέ-). When you add an unstressed possessive like μου, Greek spelling rules try to keep the stress no further than the third syllable from the end of the whole word group.

So:

τη συγκέντρωση (3rd from the end: σωστό)
τη συγκέντρωση μου → the word group gets longer and would push the accent too far back, so the accent moves:
τη συγκέντρωσή μου

This is a standard accent-shift rule with many nouns + possessive pronouns.

Why is it βοηθάει τη συγκέντρωσή μου and not βοηθάει στη συγκέντρωσή μου?

The verb βοηθάω normally takes a direct object in Greek:

βοηθάω κάποιον / κάτι = I help someone / something

So you say:

βοηθάει τη συγκέντρωσή μου = it helps my concentration

You can use σε with βοηθάω in a different meaning, like με βοηθάει σε αυτό (it helps me with this), but here the concentration itself is the direct object being helped.

Can the word order be different, e.g. can πολύ or πολύ τη συγκέντρωσή μου move around?

Yes, Greek word order is flexible. All of these are grammatical, with small differences in emphasis:

Μια μικρή μείωση… βοηθάει πολύ τη συγκέντρωσή μου. (neutral, very natural)
… βοηθάει τη συγκέντρωσή μου πολύ. (slight emphasis on how much it helps)
… τη συγκέντρωσή μου τη βοηθάει πολύ. (stronger emphasis on my concentration specifically)

The original order is the most typical and neutral-sounding.