Βάζω μικρούς στόχους κάθε μήνα και κάνω προτεραιότητα τα πιο δύσκολα πράγματα.

Μικρούς στόχους is in the accusative plural masculine.

• The verb βάζω (I put / I set) takes a direct object in the accusative.
• The noun στόχος (goal) is masculine:
  • Singular: ο στόχος (nom.), τον στόχο (acc.)
  • Plural: οι στόχοι (nom.), τους στόχους (acc.)
• The adjective μικρός must agree in gender, number, and case:
  • Singular: μικρός στόχος (nom.), μικρό στόχο (acc.)
  • Plural: μικροί στόχοι (nom.), μικρούς στόχους (acc.)

So, because στόχους is masculine accusative plural, the adjective must also be μικρούς (masc. acc. pl.).

With κάθε (every/each), Greek always uses the singular, even though the meaning is repetitive or plural-like.

• κάθε μήνα = every month
• κάθε μέρα = every day
• κάθε εβδομάδα = every week

You do not say:

• ✗ κάθε μήνες
• ✗ κάθε μήνας

Grammatically, κάθε μήνα is accusative singular, used as a time expression indicating frequency.

Literally, βάζω means I put / I place.

In this context, βάζω στόχους is an idiomatic way to say I set goals, just like in English we say “set goals” (not draw goals or make goals).

You could also say:

• Θέτω στόχους – I set goals (more formal)
• Ορίζω στόχους – I define goals (also more formal)

But βάζω στόχους is very common and natural in everyday spoken Greek.

Both βάζω and κάνω are in the present simple (ενεστώτας).

In Greek, the present tense is used for:

• Habits / routines
  Βάζω μικρούς στόχους κάθε μήνα
  = I set small goals every month (habit)

• General truths or repeated actions
  Κάνω προτεραιότητα τα πιο δύσκολα πράγματα
  = I make the most difficult things my priority (this is how I usually operate)

So the sentence describes a regular strategy or habit, not a one‑time action.

In Greek, the subject pronoun (like εγώ, εσύ, αυτός) is usually omitted, because the verb ending already shows the person.

• Βάζω clearly means I put / I set.
• Κάνω clearly means I do / I make.

You would add Εγώ only for emphasis or contrast:

• Εγώ βάζω μικρούς στόχους, όχι μεγάλους.
  I set small goals, not big ones.

In neutral statements, leaving out εγώ is more natural.

Literally, κάνω προτεραιότητα means I make (something) a priority.

Structure here:

• κάνω κάτι προτεραιότητα = I make something a priority
  • κάνω = I make/do
  • προτεραιότητα = priority (feminine noun)

So:

• κάνω προτεραιότητα τα πιο δύσκολα πράγματα
  = I make the most difficult things (into) the priority.

However, in modern Greek, more common and idiomatic ways to say “I prioritize X” are:

• βάζω σε προτεραιότητα τα πιο δύσκολα πράγματα
  I put the most difficult things in priority.
• δίνω προτεραιότητα στα πιο δύσκολα πράγματα
  I give priority to the most difficult things.

κάνω προτεραιότητα is understandable and grammatically OK, but the two expressions above are more typical.

Τα πιο δύσκολα πράγματα = the most difficult things (a specific group: the most difficult ones among all).

Breaking it down:

• τα – definite article, neuter plural
• πιο δύσκολα – more/most difficult (comparative/superlative form)
• πράγματα – things (neuter plural)

Without the article:

• πιο δύσκολα πράγματα = more difficult things (comparative, but not necessarily “the most” of all)

With πιο in Greek, we use:

• πιο δύσκολος = more difficult
• ο πιο δύσκολος = the most difficult

So τα πιο δύσκολα πράγματα corresponds to the most difficult things in English because of the definite article τα.

Yes, if the context makes it clear what you’re talking about, you can drop πράγματα:

• Κάνω προτεραιότητα τα πιο δύσκολα.
  I prioritize the most difficult (ones).

In that case:

• τα πιο δύσκολα functions as a substantivized adjective phrase – the article τα and the adjective πιο δύσκολα together act like a noun phrase: “the more difficult / the most difficult (things/tasks/etc.)”.

Greek often omits the noun when it’s obvious:

• τα καλά (the good [things])
• τα κακά (the bad [things])
• οι νέοι (the young [people])

Πράγματα is neuter plural (singular: το πράγμα = thing).

Because it’s neuter plural:

• The article must be τα (neuter plural).
• The adjective must also be neuter plural: δύσκολα.

So we get:

• τα (article, neuter pl.)
• πιο δύσκολα (adjective phrase, neuter pl.)
• πράγματα (noun, neuter pl.)

All three agree in gender (neuter) and number (plural).

Yes, that is correct, and very natural:

• …και τα πιο δύσκολα πράγματα τα κάνω προτεραιότητα.

Here:

• τα πιο δύσκολα πράγματα is the object.
• τα is a clitic object pronoun repeating the object.

This structure:

• [Object] το/τα κάνω προτεραιότητα
  literally: “[Object], I make it/them a priority.”

It adds a bit of emphasis and is a very typical Greek word order. Your original sentence is fine, but this version sounds slightly more emphatic and more colloquial/natural to many speakers.

Μήνας is the nominative singular (ο μήνας = the month).
After κάθε, we use the accusative singular:

• κάθε μήνα (every month) – accusative singular

This is a general pattern:

• ο χρόνος → κάθε χρόνο
• η μέρα → κάθε μέρα
• η εβδομάδα → κάθε εβδομάδα

So:

• μήνας = subject form (nominative)
• μήνα = object/time expression form (accusative) used after κάθε.