Nous attachons l’étiquette de retour au colis.

Because nous means we, and attachons is the verb form that goes with nous in the present tense.

The verb is attacher = to attach.

Present tense:

• j’attache = I attach
• tu attaches = you attach
• il/elle attache = he/she attaches
• nous attachons = we attach
• vous attachez = you attach / you all attach
• ils/elles attachent = they attach

French often keeps the subject pronoun, so nous attachons is the normal full form for we attach.

Because it is being conjugated for nous in the present tense.

Attacher is a regular -er verb, so with nous you normally use the ending -ons:

• infinitive: attacher
• stem: attach-
• nous form: attachons

So:

• nous attachons = we attach

This is a very common pattern with regular -er verbs:

• nous parlons
• nous regardons
• nous collons

Because French avoids having two vowel sounds collide like that. When la comes before a word beginning with a vowel or silent h, it shortens to l’.

So:

• la table
• la voiture
• but l’étiquette

This is called elision.

So l’étiquette simply means the label.

Étiquette means label or tag.

De retour literally means of return, but in natural English this becomes return label.

So:

• une étiquette de retour = a return label

This is a common French pattern:

• une carte de crédit = a credit card
• un billet de train = a train ticket
• une étiquette de retour = a return label

French often uses de where English would use a noun placed before another noun.

Because à + le contracts to au in French.

So:

• à le → au
• à les → aux

Examples:

• au colis = to the package / onto the package
• aux enfants = to the children

Here, attacher quelque chose à quelque chose means to attach something to something.

So:

• l’étiquette = the thing being attached
• au colis = the thing it is attached to

Because the French verb attacher is commonly used with à for the thing something is attached to.

Pattern:

• attacher X à Y = to attach X to Y

So:

• Nous attachons l’étiquette au colis.
• literally: We attach the label to the package.

French uses à here even when English might prefer onto in some situations. That is just the normal French construction.

Yes. Un colis is a common word for a package, parcel, or shipment, especially in mailing, delivery, and returns contexts.

Related words:

• un paquet = a package, packet, pack, parcel; often more general
• un colis = parcel/package, especially something being shipped

In a sentence about a return label, colis sounds very natural.

The order is:

• Nous = subject
• attachons = verb
• l’étiquette de retour = direct object
• au colis = prepositional phrase showing where it is attached

So the structure is:

Subject + verb + thing attached + thing it is attached to

That matches the French pattern: attacher quelque chose à quelque chose

Sometimes sur le colis could appear in certain contexts if you want to emphasize physical placement on the package. But with the verb attacher, the most natural structure is usually attacher quelque chose à quelque chose.

So:

• attacher l’étiquette au colis = natural
• mettre l’étiquette sur le colis = also natural, but with a different verb: to put the label on the package

The choice depends on the verb:

• attacher ... à ...
• mettre ... sur ...
• coller ... sur ... if you mean stick/glue onto

A careful pronunciation guide would be something like:

Noo za-ta-shon lay-ti-ket duh ruh-tohr oh ko-lee

A few helpful points:

• Nous sounds like noo
• In connected speech, there is a liaison: nous attachons sounds like noo za-ta-shon
• attachons ends with a nasal sound: -chon
• l’étiquette begins with a vowel sound, so it connects smoothly after attachons
• colis is pronounced roughly ko-lee

You do not pronounce many final consonants strongly in French, so listening to native audio is especially useful here.

Yes. The French present tense can often correspond to several English present-time meanings depending on context, including:

• We attach the return label to the package
• We are attaching the return label to the package

French does not need a special -ing form here. The simple present nous attachons can cover both ideas, and context usually makes the timing clear.

Because in étiquette de retour, retour is functioning as part of a noun phrase after de, not as a separate noun needing its own article.

This is very common in French:

• une salle de bain = a bathroom
• un ticket de caisse = a receipt
• une étiquette de retour = a return label

If you added an article, it would usually change the meaning or sound unnatural in this expression. De retour here works like for return or return-related.