Marie enlève son tablier, remet ses pantoufles et cherche ses clés.

Because French possessive adjectives agree with the thing possessed, not with the owner.

• tablier is a masculine singular noun
• so French uses son

So:

• Marie enlève son tablier = Marie takes off her apron

English uses her because Marie is female, but French looks at tablier, not at Marie.

Because pantoufles and clés are plural nouns, so the possessive adjective must also be plural:

• son / sa = singular possessed noun
• ses = plural possessed noun

So:

• ses pantoufles = her slippers
• ses clés = her keys

Also, ses can mean his, her, or sometimes their, depending on the context. Here it clearly means her, because the subject is Marie.

Remet comes from remettre, which often means to put back, to put on again, or to put back in place.

So here:

• met ses pantoufles = puts on her slippers
• remet ses pantoufles = puts her slippers back on / puts them on again

The sentence suggests that she had taken them off earlier, or that she is returning to them after doing something else.

Because in French, chercher already includes the idea of looking for.

So:

• chercher ses clés = to look for her keys

English needs for, but French does not.

Compare:

• Je cherche mon téléphone. = I’m looking for my phone.
• not Je cherche pour mon téléphone.

This is a very common difference between English and French.

Because one subject can apply to several verbs in a series.

So:

• Marie enlève son tablier, remet ses pantoufles et cherche ses clés.

means:

• Marie takes off her apron,
• puts her slippers back on,
• and looks for her keys.

French works like English here. You can list several actions after one subject without repeating it each time.

This is a spelling and pronunciation change that happens in some verb forms.

The infinitive is:

• enlever

But in the present tense:

• j’enlève
• tu enlèves
• il/elle enlève
• ils/elles enlèvent

The e changes to è before a syllable with a silent e. This helps keep the pronunciation natural.

So in your sentence:

• Marie enlève = elle enlève

That is why you see è there.

It is the present tense.

French present tense can often correspond to either:

• the simple present in English:
  Marie takes off her apron, puts her slippers back on, and looks for her keys.

or

• the present progressive:
  Marie is taking off her apron, putting her slippers back on, and looking for her keys.

Which English version sounds better depends on the context. French does not always mark that distinction as clearly as English does.

A rough guide:

• Marie → ma-ree
• enlève → ahn-LEV
• tablier → ta-blee-ay
• remet → ruh-MEH
• pantoufles → pahn-TOOFL
• cherche → shersh
• clés → klay

A few useful notes:

• final consonants are often silent in French
• the s in ses is pronounced like say
• clés sounds like clay
• cherche has the French r, which is harder and farther back in the throat than English r

In this sentence, yes, because slippers are normally understood as a pair, so French usually uses the plural:

• ses pantoufles = her slippers

You could use the singular if you were talking about just one slipper:

• une pantoufle = one slipper

But in ordinary everyday situations, the plural is the natural choice.

Yes. By itself, ses is not specifically her.

It can mean:

• his
• her
• sometimes their when the owner is singular they in English, or in some contexts depending on style

French does not choose ses based on the gender of the owner. The meaning comes from context. In this sentence, because the subject is Marie, we understand:

• ses clés = her keys