La petite a commencé à pleurer quand elle a glissé sur le carrelage mouillé.

In French, an adjective can sometimes be used as a noun when the context makes the meaning clear.

So la petite literally means the little one or the small one, but in many everyday contexts it refers to the little girl. The article la tells you it is feminine singular, so we know it refers to a female person.

Depending on context, la petite could mean:

• the little girl
• the younger daughter
• the small one (if you are comparing people or things)

Here, it most naturally means the little girl.

This is the verb commencer à + infinitive, which means to start doing something or to begin to do something.

So:

• a commencé = started / began
• à pleurer = to cry

Together:

• a commencé à pleurer = started to cry

Many French verbs are followed by another verb in the infinitive. After commencer, French normally uses à before that infinitive.

Because commencer usually takes à before another verb.

Examples:

• commencer à parler = to start speaking
• commencer à courir = to start running
• commencer à pleurer = to start crying

This is just part of the verb pattern you need to learn:

• commencer à + infinitive

English often uses to here, but French uses à.

A commencé is the passé composé, which is commonly used for a completed action in the past.

Here, the sentence describes a specific event:

• the girl slipped
• then she started crying

These are both viewed as completed past actions, so passé composé is natural:

• a commencé
• a glissé

If you used commençait, that would be the imparfait, which would give a more ongoing or background sense, such as she was starting to cry. That is less natural for this simple sequence of events.

Because glisser normally takes avoir in the passé composé.

So:

• elle a glissé = she slipped

Some movement verbs use être, but not all of them. Glisser is one of the many verbs that uses avoir.

Compare:

• elle est tombée = she fell
• elle a glissé = she slipped

So even though both involve movement, the auxiliary verb is different.

Because both actions are seen as specific, completed events in the past.

The sentence tells a short sequence:

1. she slipped
2. she started crying

French often uses the passé composé for this kind of event narration.

In English, we also often use the simple past for both:

• The little girl started crying when she slipped on the wet tile floor.

French does the same idea with passé composé:

• a commencé
• a glissé

Quand means when.

In this sentence, it introduces the moment that triggered the crying:

• quand elle a glissé = when she slipped

So it connects the two actions:

• she started crying
• when she slipped

It is a very common word for linking events in time.

The verb glisser can mean to slide or to slip, depending on context.

Here, because the floor is wet, the natural English meaning is slipped:

• elle a glissé sur le carrelage mouillé = she slipped on the wet tile floor

If the context were different, it could mean slid:

• Le livre a glissé de la table. = The book slid off the table.

So the context tells you which English word fits best.

Le carrelage refers to tiling or a tiled surface, especially a tiled floor.

In this sentence, sur le carrelage mouillé means something like:

• on the wet tiled floor
• on the wet tiles

French uses carrelage where English often prefers a phrase like tile floor or tiles.

So it is not just one tile; it refers to the tiled surface.

Because most French adjectives come after the noun.

So:

• le carrelage mouillé = the wet tiled floor / the wet tiling

Here:

• carrelage = noun
• mouillé = adjective describing it

Some common adjectives come before the noun, but many, including mouillé, normally come after.

Because mouillé agrees with carrelage, not with elle.

• carrelage is masculine singular
• so the adjective is masculine singular too: mouillé

If the noun were feminine singular, you would use mouillée:

• la chaussée mouillée = the wet road

So in the sentence:

• sur le carrelage mouillé the adjective matches carrelage.

You could translate it literally that way, but it would sound unnatural in normal English.

A more natural translation would be:

• The little girl started crying when she slipped on the wet tile floor.

This is a good example of how French and English do not always match word-for-word:

• la petite is often best translated as the little girl
• a commencé à pleurer is often more natural as started crying
• carrelage is often better rendered as tile floor or tiles
• a glissé is better as slipped in this context

So the best translation is usually the most natural one, not the most literal one.