Le bébé dort dans la poussette pendant que nous regardons les jouets.

In French, nouns usually need an article much more often than in English. So le bébé is the normal way to say the baby.

• le = the for a masculine singular noun
• bébé = baby

If you wanted to say a baby, you would use un bébé instead.

French nouns have grammatical gender, and bébé is usually treated as masculine by default, especially when the baby’s sex is unknown or irrelevant.

So:

• le bébé = the baby
• un bébé = a baby

If you specifically wanted to refer to a baby girl in another way, you might use a different noun such as la petite fille, but bébé itself is commonly masculine in grammar.

Dort is the third-person singular present tense form of dormir, which means to sleep.

The present-tense forms are:

• je dors
• tu dors
• il / elle / on dort
• nous dormons
• vous dormez
• ils / elles dorment

Because the subject is le bébé = the baby, French uses the il/elle/on form: dort.

French often uses the simple present where English might use the present progressive.

So:

• Le bébé dort can mean The baby sleeps or The baby is sleeping
• nous regardons can mean we look at or we are looking at

In this sentence, the present tense shows two actions happening at the same time.

Dans usually means in or inside. A baby is thought of as being in a stroller, so dans la poussette is the natural phrase.

• dans = in
• la poussette = the stroller

English sometimes uses in the stroller too, so this part matches quite closely.

French usually keeps an article before a noun, even after a preposition.

So French says:

• dans la poussette

where English might sometimes think more loosely in terms of just in stroller, but standard English also says in the stroller. In French, leaving out the article here would sound wrong.

Also, la tells you that poussette is a feminine noun.

Pendant que means while and introduces a whole clause with a subject and a verb.

Here:

• pendant que nous regardons les jouets = while we are looking at the toys

You use:

• pendant
  • noun
    Example: pendant la sieste = during the nap
• pendant que
  • clause
    Example: pendant que nous regardons les jouets

So que is needed because what follows is a full clause, not just a noun.

Sometimes, but not with exactly the same feel.

• pendant que emphasizes that two actions are happening at the same time
• quand usually means when

In this sentence, pendant que is better because the idea is clearly while we are looking at the toys. It highlights simultaneity.

Because regarder takes a direct object in French. It does not use a preposition here.

So:

• regarder quelque chose = to look at something

That gives:

• nous regardons les jouets = we are looking at the toys

This is different from some other French verbs that do need a preposition.

This is a very common question.

• regarder = to look at, to watch
  This suggests deliberate attention.
• voir = to see
  This is more about perception.

In this sentence, nous regardons les jouets means we are actively looking at the toys, so regarder is the right choice.

Les jouets means the toys, so it suggests specific toys, or toys that are understood from the situation.

• les jouets = the toys
• des jouets = some toys

In context, French often uses les when the toys are identifiable to the speaker and listener, even if English might sometimes sound less specific.

Yes. In everyday spoken French, on is very often used instead of nous.

So these both mean we are looking at the toys:

• nous regardons les jouets
• on regarde les jouets

The version with nous is perfectly correct and a bit more formal or careful. The version with on is very common in conversation.

A few useful pronunciation notes:

• bébé sounds roughly like bay-bay
• dort sounds roughly like dor
  The final t is silent.
• poussette sounds roughly like poo-set
• regardons sounds roughly like ruh-gar-don
  The final s is silent.
• jouets sounds roughly like zhou-ay
  The final s is silent.

Also, there is no liaison between nous and regardons, because regardons starts with a consonant sound.