Escribe tu nombre en el folio antes de entregar el examen.

Escribe is the tú imperative form of escribir. It is used to give an instruction or command to one person you address informally.

• escribir = to write
• escribes = you write / you are writing
• escribe = write!

In exam instructions, Spanish often uses the imperative because the sentence is telling the student what to do.

Yes. In Spanish, subject pronouns are often omitted because the verb form already shows who the subject is.

So:

• Escribe tu nombre...
• Tú escribe tu nombre...

The second version sounds unnatural in most normal contexts. Spanish usually prefers to leave tú out unless you want extra emphasis or contrast.

Because tu here is a possessive adjective meaning your.

Spanish distinguishes:

• tu = your
• tú = you

So:

• tu nombre = your name
• tú = you

The accent mark changes the meaning.

In Spain, folio usually means a sheet of paper, especially the standard kind used in school, offices, and exams.

It does not usually mean folder or leaflet. In this sentence, it refers to the paper on which you are writing.

A learner may also hear:

• hoja = sheet/page
• papel = paper
• folio = sheet of paper, very common in Spain

So en el folio is a very natural Spain Spanish way to say on the sheet of paper.

Spanish often uses en where English uses on for writing on paper or putting something on a surface in a more general sense.

So:

• escribe tu nombre en el folio = write your name on the sheet of paper

Even though English says on, Spanish normally says en here.

After antes, Spanish normally uses de before an infinitive.

Pattern:

• antes de + infinitive

So:

• antes de entregar = before handing in / before submitting

This is a very common structure:

• antes de salir = before leaving
• antes de comer = before eating
• antes de empezar = before starting

Without de, the sentence would be ungrammatical.

Yes, entregar basically means to hand over, to deliver, or to submit, depending on context.

In an exam context, entregar el examen means:

• to hand in the exam
• to submit the exam paper

So this is a very common school/classroom verb.

Spanish often uses the definite article where English might prefer a possessive.

Here, el examen is understood from the situation: it is the exam the student is doing and will hand in.

Both can work, but they sound slightly different:

• entregar el examen = hand in the exam
• entregar tu examen = hand in your exam

The version with el is very natural because the context already makes it clear whose exam it is.

Yes. That word order is perfectly correct.

Spanish is flexible enough to put the time phrase first:

• Escribe tu nombre en el folio antes de entregar el examen.
• Antes de entregar el examen, escribe tu nombre en el folio.

Both mean the same thing. The second version puts more focus on the timing: before handing in the exam.

The form of the imperative would change.

For usted:

• Escriba su nombre en el folio antes de entregar el examen.

For vosotros:

• Escribid vuestro nombre en el folio antes de entregar el examen.

For ustedes:

• Escriban su nombre en el folio antes de entregar el examen.

Notice that the possessive usually changes too:

• tu nombre for tú
• su nombre for usted/ustedes
• vuestro nombre for vosotros

It is understandable everywhere, but folio is especially typical of Spain.

In many parts of Latin America, people might be more likely to say something like:

• Escribe tu nombre en la hoja...
• Escribe tu nombre en el papel...

Also, in Spain, instructions to students may use tú or vosotros more freely than in many Latin American contexts, where usted or ustedes may be preferred in formal situations.

So the sentence sounds very natural in Spain Spanish.