Quand l’eau bout, j’enlève le couvercle et je verse les pâtes dans la passoire.

Because French normally shortens le or la to l’ before a vowel sound. This is called elision.

So:

• la eau → l’eau

You see the same thing in:

• l’homme
• l’école
• l’huile

Bout is the il/elle/on form of the verb bouillir, which means to boil.

Here, the subject is l’eau, which is singular, so French uses the singular verb form:

• l’eau bout = the water boils / is boiling

A quick present-tense pattern for bouillir:

• je bous
• tu bous
• il/elle bout
• nous bouillons
• vous bouillez
• ils/elles bouillent

So bout may look unusual, but it is the correct form.

French often uses the present tense for:

• instructions
• recipes
• demonstrations
• sequences of actions

So this sentence reads naturally as a recipe-style description:

• Quand l’eau bout, j’enlève le couvercle...

English often does something similar in instructions:

• When the water boils, I remove the lid...

It can describe either:

• a general procedure, or
• the next step in a set of instructions

Because je becomes j’ before a vowel sound.

So:

• je enlève → j’enlève

This is another case of elision, just like l’eau.

Also, in this sentence, j’enlève is the verb enlever meaning to remove / take off. It is not the pronoun en plus another verb. The word is simply enlever.

Here enlever means to remove or to take off.

So:

• j’enlève le couvercle = I remove the lid / I take the lid off

This verb is very common. For example:

• enlever son manteau = to take off one’s coat
• enlever un objet = to remove an object

In French, pasta is normally plural:

• les pâtes

So:

• je verse les pâtes... = I pour the pasta...

Be careful not to confuse it with la pâte (singular), which usually means:

• dough
• pastry
• batter
• paste

Examples:

• la pâte à pizza = pizza dough
• les pâtes = pasta

The accent in pâtes is a circumflex: â.

In modern French, the circumflex often:

• reflects older historical spelling,
• can slightly affect pronunciation,
• and sometimes helps distinguish words.

Here it helps distinguish:

• pâtes = pasta
• pattes = animal legs / paws

So it is important for spelling and sometimes for meaning, even if pronunciation differences are not always huge for all speakers.

French uses articles more often than English does. In a context like cooking, French naturally says:

• le couvercle = the lid
• la passoire = the colander / strainer

Even when English might sometimes say a lid or simply leave things less explicit, French often prefers the definite article when the object is understood from the situation.

In a kitchen context, there is a specific lid and a specific colander being used, so le and la sound natural.

Dans means in or into, depending on the context.

Here:

• je verse les pâtes dans la passoire

means that the pasta is being poured into the colander.

French commonly uses dans when something goes inside a container or space.

Compare:

• dans la casserole = into the saucepan / in the saucepan
• dans un bol = into a bowl
• dans la passoire = into the colander

French usually keeps the subject pronoun clearly stated before each conjugated verb, especially in ordinary speech and writing.

So:

• j’enlève le couvercle et je verse les pâtes...

is more natural and clearer than leaving the second je out.

English also often repeats the subject:

• I remove the lid and I pour the pasta...

Sometimes French can omit the second subject in certain styles, but repeating it is very normal.

Not all final letters are pronounced in French.

A rough pronunciation guide is:

• Quand l’eau bout → kahn loh boo
• j’enlève → zhahn-lev
• le couvercle → luh koo-verkl
• et je verse → ay zhuh vehrs
• les pâtes → lay paht
• dans la passoire → dahn lah pah-swahr

A few useful points:

• t in bout is silent.
• The final s in pâtes is silent.
• quand has a nasal vowel, so it does not sound like English kwand.
• j in je sounds like the s in measure.

So yes: several final letters in this sentence are written but not pronounced.