"He is drinking a glass."
Translation:Il boit un verre.
Boire is the infinitive form of the verb: "to drink"
It is conjugated like this:
I recommend that you find and use a conjugation site. It is good practice to write out the most commonly used verbs until it comes naturally without thinking. Here's one website: http://la-conjugaison.nouvelobs.com/du/verbe/
I did not understand neither English nor French parts th What does this mean?
The English sentence here is really awkward, in my opinion. Basically "il boit un verre" means "he's having a drink". I don't know why they chose to have the literal translation in the English to French exercise, but I know that "he's having a drink" is accepted as the English translation when you're given the French sentence.