Je repasse ma chemise avant de partir.

That is a very common question, because repasser has several meanings.

In everyday French, repasser can mean:

• to pass by again
• to go over again
• to review
• to iron

In the sentence Je repasse ma chemise avant de partir, the object ma chemise makes the meaning clear: it means I iron my shirt before leaving.

So here:

• Je repasse = I iron
• ma chemise = my shirt

French often relies on context like this.

Repasse is the 1st person singular present tense form of repasser.

The verb is conjugated like a regular -er verb in the present:

• je repasse = I iron
• tu repasses
• il / elle repasse
• nous repassons
• vous repassez
• ils / elles repassent

So Je repasse ma chemise literally means I iron my shirt.

Because chemise is a feminine singular noun.

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

• mon = my + masculine singular noun
• ma = my + feminine singular noun
• mes = my + plural noun

So:

• mon pull = my sweater
• ma chemise = my shirt
• mes chaussures = my shoes

Since chemise is feminine, you use ma.

Because French usually does not need a separate word like am in this kind of sentence.

In English, you say:

• I am ironing my shirt or
• I iron my shirt

In French, the simple present je repasse can cover both ideas depending on context:

• I iron
• I am ironing

So Je repasse ma chemise can mean either a general present or an action happening around now, depending on the situation.

Because after avant followed by a verb in the infinitive, French uses de.

So the pattern is:

• avant de + infinitive

Examples:

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

So in your sentence:

• avant de partir = before leaving

You cannot say avant partir.

Because after avant de, French uses the infinitive when the subject is the same.

Here, the person doing both actions is je:

• Je repasse
• Je pars

Since the same person does both, French says:

• Je repasse ma chemise avant de partir.

Literally: I iron my shirt before to leave
Natural English: I iron my shirt before leaving.

French uses:

• avant de + infinitive when the subject is the same
• avant que + subjunctive when the subject is different

Same subject:

• Je repasse ma chemise avant de partir. = I iron my shirt before leaving.

Different subject:

• Je repasse ma chemise avant qu’il parte. = I iron my shirt before he leaves.

So avant de partir is correct here because I am both the one ironing and the one leaving.

Because partir and quitter do not mean exactly the same thing.

• partir = to leave, to go away, to depart
• quitter = to leave something or someone

Examples:

• Je pars. = I’m leaving.
• Je quitte la maison. = I’m leaving the house.
• Je quitte mon travail. = I’m leaving my job.

In avant de partir, the idea is simply before leaving / before going away, so partir is the natural choice.

Yes, in theory repasser can sometimes carry the idea of doing something again, because of the prefix re-.

But in everyday usage, repasser une chemise usually just means to iron a shirt, not necessarily to iron it again.

So in most contexts:

• Je repasse ma chemise = I iron my shirt

If you really want to emphasize again, French would often make that clearer with context or another word:

• Je repasse encore ma chemise. = I’m ironing my shirt again.

It can be either, depending on context.

The French present tense is flexible.
Je repasse ma chemise avant de partir could mean:

• a habit: I iron my shirt before leaving
• what I’m doing now / around now: I’m ironing my shirt before leaving

If you want to make the action more explicitly ongoing, spoken French often uses:

• Je suis en train de repasser ma chemise avant de partir. = I’m in the middle of ironing my shirt before leaving.

But the original sentence is completely normal.

A careful pronunciation is roughly:

zhuh ruh-pass ma shuh-meez ah-vahn duh par-teer

A few useful points:

• Je sounds like zhuh
• repasse has a clear a sound in the second syllable
• chemise sounds like shuh-meez
• avant ends with a nasal vowel
• partir ends with a pronounced r

Also, the final -s of repasse is not pronounced.

The word order is very standard French:

• Je = subject
• repasse = verb
• ma chemise = direct object
• avant de partir = time expression

So the structure is:

Subject + verb + object + time phrase

This is very natural and straightforward in French.

Yes, absolutely.

Both are correct:

• Je repasse ma chemise avant de partir.
• Avant de partir, je repasse ma chemise.

The meaning stays the same. The second version just puts the time expression first for emphasis or style.