Όταν ο μικρός είναι ανυπόμονος, αρχίζει να γκρινιάζει πριν από το φαγητό.

In a sentence like this, όταν can often be understood as when or whenever, depending on context.

Here the sentence sounds general/habitual: every time the child gets impatient, he starts whining before food. So in natural English it can feel close to whenever.

A useful pattern is:

Όταν + present, present
= something that happens regularly or generally

So this sentence is not about one single occasion only; it describes a repeated situation.

The comma separates the when-clause from the main clause:

• Όταν ο μικρός είναι ανυπόμονος = when the little one is impatient
• αρχίζει να γκρινιάζει πριν από το φαγητό = he starts whining before the meal

Greek commonly uses a comma after an introductory subordinate clause, just as English often does with When... , ....

Ο μικρός literally means the little one or the little boy. In context, it often just means the child.

Greek very often uses an adjective with the article as a noun:

• ο μικρός = the little one / the boy
• η μικρή = the little one / the girl
• οι μικροί = the children / the little ones

So μικρός is originally an adjective meaning small, little, young, but here it functions like a noun because of the article ο.

Using ο μικρός can sound more personal or natural than repeating το παιδί.

It can mean either in different contexts, but here it most naturally means young / little rather than physically small.

So ο μικρός is best understood as:

• the little one
• the young one
• often simply the child

Greek often uses μικρός in family or everyday speech to refer to a child.

Yes. Ανυπόμονος is an adjective, and it must agree with the person it describes.

Here:

• ο μικρός = masculine singular
• so the adjective is also masculine singular: ανυπόμονος

Compare:

• ο μικρός είναι ανυπόμονος = the little boy/child is impatient
• η μικρή είναι ανυπόμονη = the little girl is impatient
• το παιδί είναι ανυπόμονο = the child is impatient

This is standard adjective agreement in Greek.

Because the sentence describes a state: the child is impatient.

• είναι ανυπόμονος = is impatient

If you wanted to emphasize the change into that state, Greek could use a different structure, such as something meaning becomes impatient. But here the sentence simply states the condition that leads to the next action.

So the sequence is:

1. he is impatient
2. he starts whining

After αρχίζω meaning begin/start, Greek normally uses να plus a verb:

• αρχίζω να... = I begin to...
• αρχίζει να γκρινιάζει = he starts to whine

Here να introduces the second verb, much like English to in starts to whine.

This is a very common Greek structure:

• αρχίζω να μιλάω = I start talking
• αρχίζει να τρέχει = he starts running
• άρχισαν να γελάνε = they started laughing

Because after να, Greek often uses the present/imperfective stem when the action is seen as ongoing, repeated, or in progress.

So:

• αρχίζει να γκρινιάζει = he starts whining / starts to whine

This fits well because whining is an action that can continue for a while, not just a single instant.

Learners often notice that Greek cares a lot about aspect, not just tense. Here the form suggests the action unfolds or continues.

Γκρινιάζω means something like:

• whine
• complain
• grumble
• fuss

For a child, whine is often the best match. It is a very everyday word and sounds natural in family situations.

It is not especially formal. It is common spoken Greek.

Yes, both are possible in many contexts.

• πριν από το φαγητό = before the meal / before food
• πριν το φαγητό = also before the meal

The version with από is a little fuller and very clear. In everyday Greek, πριν may appear with or without από before a noun.

So in this sentence, πριν από το φαγητό is completely natural.

Greek uses the definite article much more often than English.

So το φαγητό can mean:

• the meal
• the food
• sometimes just food, depending on context

In this sentence, it most naturally refers to the expected meal time, so το φαγητό is very normal Greek.

English often drops the article where Greek keeps it.

Most naturally, it describes a habitual/repeated situation.

That comes from the use of the present tense in both clauses:

• είναι
• αρχίζει
• γκρινιάζει

So the sense is:

Whenever the little one gets impatient, he starts whining before the meal.

If Greek wanted to describe one specific past event, the forms would usually be different.

Greek word order is fairly flexible, though not completely free.

The sentence as given is very natural:

Όταν ο μικρός είναι ανυπόμονος, αρχίζει να γκρινιάζει πριν από το φαγητό.

But other orders are possible for emphasis, for example:

• Όταν είναι ανυπόμονος ο μικρός, αρχίζει να γκρινιάζει...
• Ο μικρός αρχίζει να γκρινιάζει πριν από το φαγητό όταν είναι ανυπόμονος.

These alternatives may sound slightly different in focus, but the original version is the most straightforward and neutral for a learner.

Because Greek verb endings already show the person and number.

• αρχίζω = I start
• αρχίζεις = you start
• αρχίζει = he/she/it starts

So Greek does not need to say he unless it wants extra emphasis or contrast.

The subject is already clear from:

1. the verb ending -ει
2. the earlier noun phrase ο μικρός

So a separate pronoun would usually be unnecessary.