Avant de partir, je mets mon permis dans mon sac.

In French, avant must be followed by de when the next verb is in the infinitive.

So:

• avant de partir = before leaving / before I leave
• not avant partir

This is a fixed pattern:

• avant de manger = before eating
• avant de dormir = before sleeping

So avant de + infinitive is the normal structure here.

French often uses the infinitive after avant de when the subject is the same as in the main clause.

Here, the person who is leaving is also the person who puts the permit in the bag:

• je mets = I put
• partir = to leave

So French prefers:

• Avant de partir, je mets... = Before leaving, I put...

If the subject changes, French usually uses avant que + a conjugated verb:

• Avant qu’il parte, je lui parle. = Before he leaves, I speak to him.

Because mettre is an irregular verb, and its je form in the present tense is je mets.

Present tense of mettre:

• je mets
• tu mets
• il/elle/on met
• nous mettons
• vous mettez
• ils/elles mettent

So the -s is part of the correct form for je.

Mettre is a very common verb meaning to put, to place, or sometimes to wear, depending on context.

In this sentence:

• je mets mon permis dans mon sac = I put my license in my bag

Other examples:

• Je mets les clés sur la table. = I put the keys on the table.
• Je mets une veste. = I put on / wear a jacket.

So here it clearly means put.

Because in French, possessive adjectives like mon, ton, son, etc. usually replace the article.

So you say:

• mon permis = my license
• mon sac = my bag

Not:

• le mon permis
• un mon sac

This is different from English, but it is completely normal in French.

Yes. Both permis and sac are masculine nouns.

So the possessive adjective is mon:

• mon permis
• mon sac

French possessive adjectives agree with the noun possessed, not with the owner.

For example:

• mon livre = my book
• ma voiture = my car

Even if the speaker is female, she would still say:

• mon permis
• mon sac

because the nouns themselves are masculine.

Here, permis usually means license, especially driver’s license, depending on context.

Very often, French speakers say:

• permis de conduire = driver’s license

But in everyday speech, permis alone often refers to that.

The word permis can also relate to permission in other contexts, but in a sentence like putting it in a bag before leaving, license is the natural meaning.

Because dans means in / inside, which is what you need here.

• dans mon sac = in my bag

French uses dans for being inside something:

• dans la boîte = in the box
• dans la voiture = in the car

à would not work here for location inside a bag, and en mon sac is not correct French.

It is placed first to set the time frame: before leaving.

French often puts time expressions at the beginning of a sentence, just like English can:

• Avant de partir, je mets mon permis dans mon sac.
• Je mets mon permis dans mon sac avant de partir.

Both are grammatical. The version with Avant de partir first sounds a little more like setting the scene or emphasizing the moment.

The comma is normally used when this introductory phrase comes at the beginning of the sentence.

So:

• Avant de partir, je mets mon permis dans mon sac.

This helps readability and matches standard punctuation.

If the phrase comes at the end, there is no comma:

• Je mets mon permis dans mon sac avant de partir.

Je mets is in the present tense.

French often uses the present tense for habitual actions or things someone normally does:

• Avant de partir, je mets mon permis dans mon sac. = Before leaving, I put my license in my bag / I put my license in my bag before leaving.

Depending on context, English might use:

• simple present for routine
• present progressive in some situations
• even a more flexible phrasing in translation

But in French, the present tense is very natural here.

Permis is pronounced roughly like pehr-mee.

A few useful points:

• the final s is normally silent
• the stress is not strong like in English
• the r is the French r

So:

• permis ≈ pehr-mee

This is true whether it means license or appears in other expressions.

Yes, that is possible, but it is slightly different in nuance.

• mettre = to put
• ranger = to put away / to store / to tidy away

So:

• je mets mon permis dans mon sac = I put my license in my bag
• je range mon permis dans mon sac = I put my license away in my bag

Mettre is the more neutral, basic verb. Ranger suggests putting it in its proper place a bit more deliberately.