Learn French: L'étudiant doit faire cet exercice pour réussir. - The student must do this exercise to succeed.

In English, we often just say "to succeed" to explain why we are doing something. In French, when you want to express "in order to" do something, you use pour followed by an infinitive verb (the unconjugated dictionary form, like réussir).

Why is "this exercise" translated as cet exercice instead of ce exercice?

The word exercice is masculine, so you would normally use ce for "this". However, because exercice starts with a vowel, ce changes to cet to make pronunciation smoother and avoid two vowel sounds clashing.

Why is faire not conjugated?

In French, when you have two verbs back-to-back that share the same subject, only the first one is conjugated. Since doit (must) is already conjugated to match L'étudiant, the second verb faire (to do) stays in its infinitive form.

Where does the word doit come from?

It is the conjugated form of the irregular verb devoir, which means "must" or "to have to". The student (l'étudiant) acts as the "he/it" subject (il), so we use the form doit.