Relis ce paragraphe avant de l’envoyer.

Because relire means to read again / to reread, while lire just means to read.

• lis = read
• relis = read again / reread

So Relis ce paragraphe means Reread this paragraph.

Also, Relis is the tu imperative form of relire.

This is because the sentence is a command. In French, the imperative normally leaves out the subject pronoun.

Compare:

• Tu relis ce paragraphe. = You reread this paragraph.
• Relis ce paragraphe. = Reread this paragraph.

So French does not say Tu relis ! when giving a normal command.

Because it comes from the verb relire, and the tu imperative form keeps the -s here.

This can confuse learners because with many -er verbs, the tu imperative drops the -s:

• Tu regardes → Regarde !

But with verbs like lire / relire, the -s stays:

• Tu lis → Lis !
• Tu relis → Relis !

So Relis is completely regular for this verb.

Because paragraphe is masculine singular and begins with a consonant sound.

French uses:

• ce before a masculine singular noun starting with a consonant sound
• cet before a masculine singular noun starting with a vowel or silent h
• cette for feminine singular nouns

Examples:

• ce paragraphe
• cet article
• cette phrase

So ce paragraphe is the correct form.

It means before sending it or before you send it.

The pattern is:

• avant de + infinitive

French uses this structure when the subject is the same as in the main clause. In other words, the person who rereads the paragraph is also the person who sends it.

So:

• Relis ce paragraphe avant de l’envoyer.
• literally: Reread this paragraph before sending it.

Because avant de is used before an infinitive, while avant que is used before a full clause with its own verb.

Compare:

• avant de l’envoyer = before sending it
• avant que tu l’envoies = before you send it

Both can refer to a similar idea, but the grammar is different:

• avant de + infinitive
• avant que + subjunctive

In your sentence, French chooses the simpler infinitive structure.

l’ is the direct object pronoun le, shortened before a vowel.

It refers back to ce paragraphe.

So:

• le = it for a masculine noun
• le envoyer is impossible
• before a vowel, le becomes l’
• so you get l’envoyer

In other words, l’envoyer means to send it.

In French, object pronouns usually come before the verb they belong to, including before an infinitive.

So French says:

• l’envoyer = to send it

not:

• envoyer-le in this structure

This is normal French word order with infinitives.

A useful comparison:

• Je vais l’envoyer. = I’m going to send it.
• Avant de l’envoyer... = Before sending it...

The apostrophe shows elision. French often drops a vowel before another vowel sound.

Here:

• le + envoyer becomes l’envoyer

This is done for smoother pronunciation.

You see the same thing in many other cases:

• je aime → j’aime
• le ami → l’ami
• ne oublie pas → n’oublie pas

Yes. The form of the imperative changes depending on who is being addressed.

• Relis ce paragraphe... = talking to one person informally
• Relisez ce paragraphe... = talking to one person formally or more than one person
• Relisons ce paragraphe... = Let’s reread this paragraph...

So the original sentence uses the tu form.

Yes, grammatically you could, but the meaning changes slightly.

• Lis ce paragraphe = Read this paragraph
• Relis ce paragraphe = Reread this paragraph

So the original sentence suggests that the paragraph has probably already been written or read once, and now the speaker wants the person to check it again before sending it. That is why Relis is the more natural choice here.