Avant d’envoyer le dossier, Marie attache le brouillon avec un trombone puis cherche l’agrafeuse.

Because French normally shortens de to d’ before a vowel sound. This is called elision.

• de envoyer → d’envoyer
• So avant d’envoyer literally means before sending or before she sends

You will see this a lot:

• essayer d’apprendre
• oublier dacheter? actually d’acheter
• avant d’ouvrir

Avant de + infinitive is the normal pattern when the subject is the same for both actions.

In this sentence, Marie is the one doing both things:

1. sending the file
2. attaching the draft / looking for the stapler

So French uses:

• Avant d’envoyer le dossier...

If the subject changed, French would usually use avant que + subjunctive instead:

• Avant que Marie envoie le dossier, Paul relit le texte.

So the sentence uses avant de because the action is expressed with an infinitive and the doer is still Marie.

Because envoyer comes after avant de, which requires an infinitive.

So the structure is:

• Avant de + infinitive = before doing something

But attache and cherche are the main actions of the sentence, so they are conjugated:

• Marie attache
• (Marie) cherche

In other words:

• d’envoyer = dependent action
• attache / cherche = main actions

Because Marie is third person singular, and the present tense form of attacher for il / elle / on is attache.

Present tense of attacher:

• j’attache
• tu attaches
• il / elle / on attache
• nous attachons
• vous attachez
• ils / elles attachent

So with Marie, you use attache.

French often uses the present tense in ways that English may also use the present, depending on context. Here it can sound like:

• a description of what Marie does
• a habitual action
• a step in a process
• a narrative present

So Marie attache... puis cherche... can mean something like:

• Marie attaches... then looks for... or, depending on context,
• Before sending the file, Marie attaches the draft with a paperclip and then looks for the stapler.

French does not need a future form here just because the action happens before another one.

Un dossier often means file, folder, or case file, depending on context.

In this sentence, le dossier most naturally means something like:

• a file
• a document set
• a folder of papers

It does not necessarily mean a computer folder only; it can also be a physical set of documents.

Un brouillon means draft, rough copy, or first version.

It often refers to:

• a preliminary version of a text
• a messy or not-final copy
• scratch work

So le brouillon here is probably the draft version of the document Marie is handling.

Yes. In everyday French, un trombone can mean a paperclip.

It can also mean the musical instrument trombone, but context makes the meaning clear. In this sentence, because Marie is attaching papers, un trombone clearly means a paperclip.

So:

• attacher le brouillon avec un trombone = attach the draft with a paperclip

Avec means with. It introduces the object used to do the action.

So:

• attacher le brouillon avec un trombone = to attach the draft with a paperclip

This is a very common structure in French:

• écrire avec un stylo = write with a pen
• couper avec des ciseaux = cut with scissors
• ouvrir avec une clé = open with a key

French often uses the definite article where English might also say the, especially when the object is seen as specific or understood from the situation.

So cherche l’agrafeuse means:

• looks for the stapler

This suggests a particular stapler, probably the one in the office or the one Marie expects to find.

If you said une agrafeuse, it would sound more like:

• she is looking for a stapler, any stapler

Both are possible in some contexts, but l’agrafeuse points to a specific, expected stapler.

Because the subject stays the same. French does not need to repeat the subject if two verbs share it and are linked naturally.

So:

• Marie attache le brouillon avec un trombone puis cherche l’agrafeuse

means:

• Marie attaches the draft with a paperclip and then (Marie) looks for the stapler.

Repeating Marie would usually sound unnecessary here:

• Marie attache... puis Marie cherche...
  This is grammatically possible, but less natural unless you want emphasis.

Puis means then, next, or after that. It shows sequence.

So:

• attache... puis cherche... = attaches... then looks for...

This is a bit more precise than et, which simply means and.

Compare:

• Marie attache le brouillon et cherche l’agrafeuse. = Marie attaches the draft and looks for the stapler.
• Marie attache le brouillon puis cherche l’agrafeuse. = Marie attaches the draft, then looks for the stapler.

So puis emphasizes the order of actions.

Because Avant d’envoyer le dossier is an introductory time clause. The comma separates that introductory part from the main clause:

• Avant d’envoyer le dossier,
• Marie attache le brouillon...

In English, we often do the same:

• Before sending the file, Marie attaches the draft...

The comma helps the sentence read more clearly.

A close literal breakdown is:

• Avant d’envoyer le dossier = Before sending the file
• Marie attache le brouillon = Marie attaches the draft
• avec un trombone = with a paperclip
• puis cherche l’agrafeuse = then looks for the stapler

So the whole sentence is:

• Before sending the file, Marie attaches the draft with a paperclip, then looks for the stapler.

That is both quite literal and natural English.