Avant de renvoyer le produit, je lis les conditions de retour.

Because in French, avant must be followed by de when the next verb stays in the infinitive.

• avant de + infinitive = before doing
• avant + noun = before + noun
• avant que + clause = before + subject + verb

Examples:

• Avant de partir = before leaving
• Avant le repas = before the meal
• Avant que tu partes = before you leave

So avant de renvoyer le produit is the normal structure for before sending the product back.

It is in the infinitive because it comes after avant de.

In English, we often use before + -ing:

• before sending back the product

French usually uses:

• avant de + infinitive
• avant de renvoyer le produit

So the infinitive here is not unusual at all; it is the standard grammar pattern.

Yes, but renvoyer is more precise here.

• renvoyer = to send back
• retourner = to return / go back / turn over, depending on context
• rendre = to give back

In the context of returning a product, renvoyer strongly suggests mailing or shipping it back, which fits very well.

So:

• renvoyer le produit = send the product back
• retourner le produit can also be heard, but it may sound a little less specific
• rendre le produit would suggest physically giving it back, for example in a store

The phrase Avant de renvoyer le produit is an introductory phrase placed at the beginning of the sentence. French often uses a comma after this kind of opening phrase, especially when it marks a pause.

So the structure is:

• Avant de renvoyer le produit, = introductory time phrase
• je lis les conditions de retour. = main clause

The comma helps readability and sounds natural. In very short sentences, French sometimes omits such commas, but here using one is normal and clear.

The present tense here can describe a habitual action or a general practice.

So this sentence can mean something like:

• Before sending a product back, I read the return conditions.

It sounds like something the speaker normally does.

If you wanted to stress a specific future action, you might say something like:

• Avant de renvoyer le produit, je vais lire les conditions de retour.

But je lis is perfectly natural if you are describing a routine or a standard step.

Because French often talks about rules, terms, and requirements in the plural when there are several details involved.

Les conditions de retour is a very natural phrase meaning the return conditions, return terms, or return policy details.

The plural suggests there is more than one rule:

• time limit
• product state
• packaging
• refund method

You could sometimes see singular phrases such as:

• la politique de retour = return policy

But les conditions de retour is extremely common.

Because this is a common French noun + de + noun structure, where the second noun defines the type or purpose of the first.

So:

• conditions de retour = return conditions
• billet de train = train ticket
• salle de bain = bathroom

In these expressions, French often does not use an article before the second noun.

So de retour here does not mean of the return literally in a word-for-word way; it is just the normal structure for this kind of phrase.

French uses articles much more often than English does.

Here:

• le produit refers to the product in question
• les conditions refers to the relevant return conditions

English can say:

• return product
• read return conditions

But French generally needs the article:

• renvoyer le produit
• lire les conditions de retour

Leaving the articles out would sound ungrammatical in standard French.

Not in this exact form.

Use avant de when the action after before is expressed with an infinitive:

• Avant de renvoyer le produit, je lis...

Use avant que when there is a full clause with its own subject:

• Avant que je ne renvoie le produit, je lis les conditions de retour.
• Avant que vous ne renvoyiez le produit, lisez les conditions de retour.

So avant que is possible only if you add a conjugated verb and a subject. In your sentence, avant de is the natural choice.

In je lis, the s is pronounced.

So lis sounds roughly like lee plus a soft s sound: lees.

That is different from some other French verb forms where a final consonant is silent.

A quick pronunciation guide for the whole sentence:

• Avant → roughly ah-vahn
• de renvoyer → duh rahn-vwa-yay
• le produit → luh pro-dwee
• je lis → zhuh lee
• les conditions de retour → lay kohn-dee-syon duh ruh-toor

The biggest pronunciation points are:

• the nasal sound in avant
• the en nasal sound in renvoyer
• the pronounced final s in lis

The core sentence is:

• Je lis les conditions de retour.
• subject + verb + object

Then French adds the time expression at the front:

• Avant de renvoyer le produit,
  • main sentence

So the full structure is:

1. time phrase: Avant de renvoyer le produit
2. main clause: je lis les conditions de retour

This is very common in both French and English:

• Before sending the product back, I read the return conditions.

French word order here is straightforward and natural.