De oefening die de docent geeft, helpt mij om de grammatica beter te begrijpen.

Because oefening is a singular de-word. In Dutch relative clauses:

• die is used for singular de-words and for all plurals
• dat is used for singular het-words

So de oefening die... means the exercise that/which...

It introduces a relative clause and refers back to de oefening.

So the structure is:

• de oefening = the exercise
• die de docent geeft = that the teacher gives

Inside that clause, die is the object of geeft. In other words, it is the thing the teacher gives.

Because die de docent geeft is a subordinate clause, specifically a relative clause. In Dutch subordinate clauses, the finite verb usually goes to the end.

So Dutch says:

• die de docent geeft

not:

• die de docent geeft → correct
• die geeft de docent → not correct here

This is one of the biggest word-order differences from English.

Because the whole phrase De oefening die de docent geeft is the subject of the sentence.

Dutch main clauses normally follow the verb-second rule: the finite verb comes in the second position. But second position means second main element, not necessarily second word.

So here:

1. De oefening die de docent geeft = the first element, the full subject
2. helpt = the finite verb

That is why helpt comes after the entire subject phrase.

The comma marks the end of the relative clause die de docent geeft. After that, the main clause continues with helpt mij...

So the sentence is structured like this:

• main subject: De oefening ...
• inserted relative clause: die de docent geeft
• rest of main clause: helpt mij om de grammatica beter te begrijpen

The comma helps show where the inserted clause ends.

Because ik is the subject form, while mij is the object form.

Compare:

• ik help = I help
• het helpt mij = it helps me

In this sentence, the exercise is the subject, and mij is the person being helped.

Yes. Me is very common in everyday Dutch.

So these are both possible:

• helpt mij om de grammatica beter te begrijpen
• helpt me om de grammatica beter te begrijpen

The difference is mostly about stress and style:

• mij sounds more stressed, emphatic, or slightly more formal
• me is the normal unstressed form in speech

This is an infinitive construction. It tells you what the exercise helps you do.

• helpt mij = helps me
• om de grammatica beter te begrijpen = to understand the grammar better

The word te is the usual marker before an infinitive in Dutch.
The word om often introduces this kind of infinitive clause and can make the structure clearer.

With helpen, Dutch often allows variation, so you may also hear:

• helpt mij de grammatica beter te begrijpen

That is also natural.

Because beter modifies the verb begrijpen.

Dutch normally places this kind of adverb before the infinitive:

• beter begrijpen = understand better

So:

• de grammatica beter te begrijpen = to understand the grammar better

You should think of beter begrijpen as a unit.

In Dutch, it is very common to use the definite article with nouns like grammatica when talking about the subject matter or the system as a whole.

So de grammatica here means something like:

• grammar
• the grammar
• the grammar you are learning/studying

Using de grammatica sounds natural and standard in this sentence.

Yes. Dutch relative pronouns are not chosen the same way as in English.

For singular de-words, Dutch often uses die, even for people:

• de docent die daar staat = the teacher who is standing there

So die can correspond to English that, which, or who, depending on the noun it refers to and the English translation that sounds best.