Questions & Answers about Cursul de matematică este mai dificil decât alte cursuri.
Romanian marks definiteness with an ending, not with a separate word like the.
- curs = a course (indefinite)
- cursul = the course (definite)
So:
- Curs de matematică = a math course / math course (in general)
- Cursul de matematică = the math course (a specific one already known from context)
In your sentence, we are talking about a specific course that both speaker and listener know, so Romanian uses cursul (with the definite article -ul stuck to the noun).
„de” literally means „of” and is used to show what kind of course it is.
- curs de matematică = course of mathematics = math course
- curs de istorie = history course
- curs de engleză = English course
This is a very common pattern in Romanian:
curs de + [subject] to mean course in [subject].