À la récréation, les enfants jouent dans la cour, puis ils se remettent en rang.

À la récréation is a time expression meaning at recess or during recess.

French often puts time expressions at the beginning of the sentence to set the scene. English does this too: At recess, the children play...

A few useful notes:

• à here means something like at
• la récréation is a specific school break period
• The accent in À is normal because the word is à; it stays accented even at the beginning of a sentence

You could also say Pendant la récréation, which emphasizes during the whole recess period a bit more.

Not exactly.

In school French, la récréation usually means recess, breaktime, or playtime.

For an English speaker, it can look like recreation, but that is a bit of a false friend. English recreation is broader and can mean leisure activities in general. French récréation in this context is specifically the school break.

French usually needs an article where English often does not.

So:

• les enfants = the children
• in context, this can mean a specific group of children, or children in that situation

French does not usually leave plural count nouns bare the way English can. English can say Children play in the yard; French normally says Les enfants jouent dans la cour.

Jouent is the third person plural present-tense form of jouer.

• je joue
• tu joues
• il/elle joue
• ils/elles jouent

The important pronunciation point is that the -ent ending is not pronounced here.
So jouent sounds like joue.

That is very common in French present-tense verbs.

Dans la cour means in the yard or in the schoolyard.

Here, la cour refers to the school playground area or courtyard.

A native English speaker might think of court, but French cour here is not a tennis court or a court of law. In school contexts, it usually means:

• schoolyard
• playground
• courtyard

Because dans emphasizes being inside or within that space.

So:

• dans la cour = in the yard / in the courtyard

If you said à la cour, that would usually suggest something very different, such as at court in the royal sense.

For a physical place where children are playing, dans la cour is the natural choice.

Puis means then.

It shows that one action happens after another:

• first, the children play
• then, they line up again

Compared with similar words:

• et = and
• puis = then / and then
• ensuite = afterward / next

All can connect actions, but puis is very natural here because it clearly marks sequence.

French normally repeats the subject pronoun before each new conjugated verb.

So French says:

• les enfants jouent..., puis ils se remettent...

English can sometimes avoid repeating the subject:

• The children play in the yard, then line up again

French usually does not do that. It prefers the explicit subject:

• puis ils...

It comes from the reflexive verb se remettre, which literally can mean to put oneself back or to get back into a state or position.

In this sentence, se remettent en rang means:

• get back in line
• line up again

The idea is that after playing, the children return to an orderly line.

Because the verb here is reflexive.

The children are doing the action to themselves:

• they are putting themselves back into line

That is why French uses:

• se remettre

and not just:

• remettre

Very literally:

• ils se remettent en rang = they put themselves back into line

En rang is a fixed expression.

It means:

• in line
• in rows
• properly lined up

French often uses en without an article in set expressions describing a state or arrangement.

Common school phrase:

• se mettre en rang = to line up
• se remettre en rang = to line up again / get back into line

So en rang is the natural idiomatic form.

Both are possible, but they are not exactly the same.

• se mettre en rang = to line up
• se remettre en rang = to line up again / get back into line

The re- adds the idea of again or back. That fits the situation well: the children were organized, then they played at recess, and afterward they return to line formation.

It is mainly punctuation for clarity.

À la récréation is an introductory time phrase, so a comma is very natural:

• À la récréation, les enfants jouent...

It helps separate the setting from the main action. In very short sentences, French punctuation can sometimes vary, but this comma is perfectly normal and makes the sentence easier to read.