Ha nem érti a feladatot, a diák megkérdezi a tanárt.

Because the verb érteni (to understand) is being used with a definite object: a feladatot = the task / the exercise.

Hungarian has two main present-tense conjugations:

• indefinite conjugation: used when there is no object, or the object is indefinite
• definite conjugation: used when the object is definite

So:

• ért = he/she understands something in a general or indefinite sense
• érti = he/she understands it / the specific thing

Since a feladatot is definite, Hungarian uses érti.

The ending -t marks the direct object in Hungarian, similar to how English shows the object by word order.

• feladat = task, exercise
• feladatot = the task / the exercise as the object of the verb

The extra vowel -o- appears for pronunciation reasons, so the object ending here is -ot, not just -t.

So:

• érti a feladatot = understands the task

For the same reason: a tanárt is also a direct object.

In a diák megkérdezi a tanárt:

• a diák = the student → subject
• a tanárt = the teacher → object, the person being asked

So Hungarian marks the teacher with the accusative ending -t:

• tanár = teacher
• tanárt = teacher (as object)

meg- is a very common verbal prefix in Hungarian. In many verbs, it adds a sense of completion, single completed action, or result.

Compare:

• kérdezi = asks / is asking
• megkérdezi = asks (and completes the act of asking)

In this sentence, megkérdezi a tanárt means something like:

• asks the teacher
• goes and asks the teacher
• asks the teacher for clarification

You do not always translate meg- directly into English, but it often gives the verb a more complete, bounded meaning.

Hungarian often omits subject pronouns because the verb ending already shows the person and number.

For example:

• érti = he/she understands it
• megkérdezi = he/she asks him/her/it

So Hungarian does not need to say ő (he/she) unless it wants extra emphasis or contrast.

That is why the sentence can simply say:

• Ha nem érti a feladatot...
  instead of
• Ha ő nem érti a feladatot...

In Hungarian, nem is the usual word for not, and it normally comes directly before the verb.

So:

• érti = understands it
• nem érti = does not understand it

This is the standard way to negate a verb in a simple sentence.

Ha means if.

So the sentence structure is:

• Ha nem érti a feladatot = If he/she does not understand the task
• a diák megkérdezi a tanárt = the student asks the teacher

This is a normal Hungarian if-clause + main clause pattern.

Because the sentence begins with a subordinate clause introduced by ha (if), and Hungarian normally separates that clause from the main clause with a comma.

So:

• Ha nem érti a feladatot, a diák megkérdezi a tanárt.

This is similar to English:

• If he/she does not understand the task, the student asks the teacher.

Because a / az is the Hungarian definite article, equivalent to English the.

Here:

• a feladatot = the task
• a diák = the student
• a tanárt = the teacher

Hungarian uses the definite article very frequently, often in places where English also uses the.

A quick note:

• a is used before most consonant-initial words
• az is used before vowel-initial words

For example:

• a diák
• az iskola

The verb ending shows that the subject is he/she, but it does not tell you who that person is.
So if you want to say specifically the student, you include a diák.

Without it:

• Ha nem érti a feladatot, megkérdezi a tanárt. = If he/she does not understand the task, he/she asks the teacher.

With it:

• Ha nem érti a feladatot, a diák megkérdezi a tanárt. = If the student does not understand the task, the student asks the teacher.

So a diák makes the subject explicit.

Because the sentence begins with the if-clause:

• Ha nem érti a feladatot = If he/she does not understand the task

After that, the main clause begins:

• a diák megkérdezi a tanárt

This is perfectly normal in Hungarian. The subject belongs to the main clause, so it appears there.

Hungarian word order is also quite flexible, but this version is natural and neutral.

Both can be translated as asks the teacher, but there is a nuance.

• kérdezi a tanárt can sound more like is asking the teacher or simply focus on the ongoing action
• megkérdezi a tanárt often suggests a single complete act: asks the teacher / goes and asks the teacher

In this sentence, megkérdezi fits well because it describes what the student does in response to not understanding: the student asks the teacher.

It can mean several related things depending on context, including:

• task
• exercise
• assignment
• problem

In a school context, a feladat often means:

• a classroom exercise
• a question to solve
• a task in a textbook or worksheet

So here it could naturally be understood as the exercise or the task, depending on the context shown to the learner.