Guarda el folio en el archivador azul antes de salir.

Guarda is the tú imperative form of guardar, so it means put away / keep / store as a command.

• guardar = the infinitive, to put away / to keep
• guarda = put away... / keep... when speaking to one person informally

So this sentence is giving an instruction to one person.

It is informal singular, used with tú.

In Spain, the main command forms would be:

• guarda = informal singular
• guarde = formal singular
• guardad = informal plural (vosotros)
• guarden = formal plural (ustedes)

So this sentence sounds like you are speaking casually to one person.

Yes. By itself, guarda could also be the he/she/it guards form of the present tense:

• Él guarda el folio = He puts away the sheet of paper

But in this sentence, the structure and context make it clearly sound like a command: Guarda el folio... antes de salir = Put the sheet away... before leaving

In Spain, folio commonly means a sheet of paper or sometimes a page, especially in everyday office or school language.

A useful cultural note:

• In Spain, people often say un folio for a standard sheet of paper, often basically referring to A4 paper
• This is not exactly the same as the English word folio

So even if the translation says sheet of paper, the Spanish word folio is very normal in Spain.

Spanish uses articles much more often than English does.

Here, el folio means the sheet of paper. It suggests a specific sheet, probably one already known from the situation.

Compare:

• Guarda el folio = Put away the sheet of paper
• Guarda un folio = Put away a sheet of paper

So the article is important because it helps show whether the object is specific or not.

Archivador is a word for something used to store papers, such as a:

• file
• binder
• file holder
• sometimes a lever-arch file, depending on context

In this sentence, it is best understood as something like the blue file/binder where the paper should be placed.

Because with guardar, Spanish normally uses en to show the place where something is being put or stored.

• Guardar algo en... = to put/store something in...

So:

• Guarda el folio en el archivador azul = Put the sheet in the blue file/binder

English often distinguishes in and into, but Spanish very often just uses en here.

Also, a el would contract to al, but guardar algo al archivador would not sound natural in this context.

Because in Spanish, descriptive adjectives usually come after the noun.

So:

• el archivador azul = the blue file/binder

This is the normal word order in Spanish.

Also, azul does not change in the singular for masculine/feminine:

• el archivador azul
• la carpeta azul

But in the plural it becomes:

• los archivadores azules
• las carpetas azules

After antes de, Spanish normally uses the infinitive when the subject is the same as the subject of the main clause, or when the subject is general/understood.

So:

• Guarda el folio... antes de salir = Put away the sheet... before leaving

Here, the person being told to put the paper away is also the person who will leave, so the infinitive salir is used.

If the subject changes, Spanish usually uses antes de que + subjunctive:

• Guarda el folio antes de que salga Marta
• Put away the sheet before Marta leaves

So antes de salir is correct because it means before leaving.

It can mean either, depending on context.

• salir = to go out
• salir = to leave
• salir de... = to leave / go out of...

In this sentence, antes de salir most naturally means before leaving or before you go out. The exact English choice depends on the situation.

Because Spanish often leaves out subject pronouns when they are already clear from the verb form.

In English, you must say:

• You put away the sheet...
• Put away the sheet...

In Spanish, the verb form already shows the person:

• Guarda = command to tú

So there is no need to add tú, unless you want extra emphasis:

• Tú, guarda el folio...

That would sound more emphatic, and in many contexts less natural than the version without tú.

Not very naturally. Although guardar can sometimes be translated as keep, here it really means put away / store / put in.

So more natural translations would be:

• Put the sheet of paper in the blue binder before leaving.
• Put the paper away in the blue file before you leave.

The exact English wording can vary, but the Spanish idea is that the paper should be placed/stored there before the person leaves.