A tanfolyamon ma három nehéz feladat van, de a tanárnő segít.

The base word is tanfolyam, meaning course or class/course program.

The ending -on is a location ending. In this sentence, a tanfolyamon means on the course or more naturally in English, in the class / during the course.

Hungarian often uses location endings in ways that do not match English exactly, so it is best to learn tanfolyamon as the normal way to say in the course / in class here.

A is the Hungarian definite article, meaning the.

So A tanfolyamon means in the course / in the class, referring to a specific course that the speakers already know about.

Hungarian uses a/az very often, sometimes even where English might sound more natural without an article.

Yes, ma means today, and it can move.

Hungarian word order is flexible, and moving a word often changes the emphasis rather than the basic meaning.

In this sentence:

A tanfolyamon ma három nehéz feladat van...

the sentence first sets the scene with A tanfolyamon and then adds the time ma.

Other orders are possible, for example:

• Ma a tanfolyamon három nehéz feladat van.
• A tanfolyamon három nehéz feladat van ma.

These all mean roughly the same thing, but the focus sounds a little different.

In Hungarian, after numbers, the noun usually stays in the singular form.

So you say:

• három feladat = three tasks
• not három feladatok

This is completely normal Hungarian grammar. English uses plural after numbers, but Hungarian does not.

This is a very common question.

In existential sentences, where Hungarian is basically saying there is / there are, a numbered noun phrase often goes with singular van:

• Három feladat van. = There are three tasks.

So even though the meaning is plural in English, Hungarian normally uses van here.

This is especially common with quantity expressions such as:

• két könyv van
• sok ember van
• három kérdés van

Hungarian often does leave out present-tense van in sentences like:

• A feladat nehéz. = The task is difficult.

But in existential sentences, where the meaning is there is / there are, van stays:

• Három nehéz feladat van. = There are three difficult tasks.

So the rule is roughly:

• A feladat nehéz. → no van
• Három feladat van. → van is needed

Because három already works as the determiner.

In Hungarian, you do not use egy or another article together with a numeral in this kind of phrase.

So:

• három nehéz feladat = three difficult tasks

That is complete by itself.

Nehéz means difficult and it comes before the noun, just like an ordinary adjective:

• nehéz feladat = difficult task

In Hungarian, adjectives in this position do not usually show plural marking:

• egy nehéz feladat
• három nehéz feladat

not három nehezek feladat

So nehéz stays the same here.

Tanárnő means female teacher or teacher when the teacher is a woman.

It is built from:

• tanár = teacher
• nő = woman / lady

In Hungarian, tanárnő is a very common and normal word, especially in school contexts. It is not strange or overly formal.

Because it refers to a specific teacher, so Hungarian uses the definite article a:

• a tanárnő = the teacher

This is just like English the teacher, except Hungarian uses a before consonant-initial words and az before vowel-initial words.

Because segít here does not have a definite direct object.

This is connected to Hungarian's two verb conjugations. Very roughly:

• segít = used when there is no definite direct object
• segíti = used when there is a definite direct object

In this sentence:

a tanárnő segít = the teacher helps

The person being helped is not named, or it is understood from context. If you wanted, you could add something like:

• A tanárnő segít nekünk. = The teacher helps us.

So segít is the right form here.

No. Hungarian often leaves things unstated if they are clear from the situation.

So:

• A tanárnő segít. = The teacher helps.

This can mean The teacher is helping or The teacher helps us/the students, depending on context.

If you want to say who is being helped, you can add it:

• A tanárnő segít nekünk. = The teacher helps us.

De means but.

It connects the two parts of the sentence:

• A tanfolyamon ma három nehéz feladat van
• de a tanárnő segít

Hungarian normally uses a comma before de, just as English often does before but.

Yes, it is natural.

A very neutral reading is:

• A tanfolyamon = setting/location
• ma = time
• három nehéz feladat = what exists
• van = there is/are
• de a tanárnő segít = contrast: but the teacher helps

Hungarian often arranges a sentence by topic and focus, not by a fixed English-style word order. So this sentence sounds natural and well-formed.