Si tienes alguna duda, pregunta a la profesora después de clase.

Yes — pregunta can be either:

• the noun question
• the tú imperative of preguntar: ask

In this sentence, it is a command, so it means ask.

• Si tienes alguna duda, pregunta... = If you have any questions, ask...

This is very common in Spanish: the tú affirmative command often looks the same as the él/ella/usted present form.

• preguntar → pregunta
• hablar → habla
• escuchar → escucha

So here pregunta is not a noun; it is an instruction.

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

• tienes already means you have
• pregunta here means ask addressed to you informally

So tú is understood and does not need to be said.

If you added it, it would be:

• Si tú tienes alguna duda, pregunta a la profesora...

That is grammatically correct, but usually unnecessary unless you want emphasis or contrast.

Because after si meaning if, Spanish normally uses the indicative for real or possible situations.

• Si tienes alguna duda... = If you have any questions...

This is a normal, open condition, so tienes is correct.

Spanish does not say:

• Si tengas alguna duda... ❌

That sounds wrong in standard Spanish.

A useful rule:

• si + present indicative for real/possible conditions
• then the main clause can be a command, future, present, etc.

Examples:

• Si necesitas ayuda, dímelo.
• Si vienes mañana, hablamos.

Here alguna means any or some.

• alguna duda = any question / any doubt

Using una duda would sound more like one specific doubt/question, while alguna duda is broader and more natural in this kind of instruction.

This is a very common pattern in Spanish:

• Si tienes alguna pregunta...
• Si tienes algún problema...
• Si tienes alguna duda...

Also notice:

• algún before masculine singular nouns: algún problema
• alguna before feminine singular nouns: alguna duda

Because Spanish often uses singular in expressions like this where English prefers a plural.

• tener alguna duda is a very common idiomatic way to say to have any questions / to be unsure about something

So even though English often says questions, Spanish naturally says duda in the singular here.

You could also hear:

• Si tienes dudas...
• Si tienes alguna pregunta...

Those are fine too, but alguna duda is very natural and common.

That is the personal a.

In Spanish, when the direct object is a specific person, you usually put a before it.

So:

• pregunta a la profesora = ask the teacher

Other examples:

• Veo a María.
• Llama al profesor.
• Escucha a tu madre.

Even though English does not use a special word here, Spanish usually does.

Because Spanish only contracts a + el into al.

• a + el → al
• a + la stays a la

So:

• a la profesora ✅
• al profesor ✅
• al profesora ❌

Since profesora is feminine, the article is la, so there is no contraction.

Yes. La profesora means the teacher is female.

• el profesor = male teacher
• la profesora = female teacher

Spanish usually marks this distinction clearly.

In a real classroom, the speaker would choose profesor or profesora depending on the actual teacher.

Because después de clase is a very common fixed expression meaning after class.

In Spanish, school-related expressions often omit the article in this kind of general phrase:

• después de clase = after class
• antes de clase = before class

If you say después de la clase, it sounds more like after the class, referring to one specific class session more explicitly.

So both can be possible in some contexts, but después de clase is the most natural general instruction.

Because the sentence begins with the if-clause:

• Si tienes alguna duda, ...

When that introductory clause comes first, Spanish normally separates it with a comma from the main clause:

• Si tienes alguna duda, pregunta...

This is similar to English punctuation in sentences like:

• If you have any questions, ask the teacher after class.

Yes. Spanish allows some flexibility.

For example:

• Pregunta a la profesora después de clase si tienes alguna duda.

This means the same thing.

The version you were given puts the condition first:

• Si tienes alguna duda, pregunta...

That order is very natural because it sets up the situation first and then gives the instruction.

Because si without an accent means if.

• si = if

But sí with an accent usually means yes.

• sí = yes

So in this sentence, it must be si because it introduces a condition:

• Si tienes alguna duda... = If you have any questions...

This is a very common distinction in Spanish spelling.

Yes, but it changes the structure slightly.

• Pregunta a la profesora = Ask the teacher
• Pregúntale a la profesora is usually not the most natural version, because le already refers to the teacher, so repeating a la profesora can sound redundant unless you want emphasis

More natural alternatives would be:

• Pregunta a la profesora.
• Pregúntale. = Ask her.
• Hazle la pregunta a la profesora. = Ask the teacher the question.

In your sentence, pregunta a la profesora is simple and completely natural.

You would change the verbs to the usted forms:

• Si tiene alguna duda, pregunte a la profesora después de clase.

Here:

• tiene = you have (formal)
• pregunte = ask (formal command)

So the original sentence is talking to one person informally, using tú. The formal version uses usted.