The teacher I like is so popular with all the students I can hardly get a class with him.
My favourite teacher is well-liked by all the students so it makes it hard to schedule a class with him.
ーThe teacher I like is so popular with all the students I can hardly get a class with him.
「好きな先生が人気で、なかなか彼のクラスが取れない。」
popular で「人気のある・評判の良い」
I can hardly ... で「なかなか…できない」
ーMy favourite teacher is well-liked by all the students so it makes it hard to schedule a lesson with him.
「お気に入りの先生が生徒みんなからとても人気なので、彼のレッスンを入れるのが難しい。」
well-liked で「好かれて・人気があって」
schedule a lesson で「レッスンを入れる・予定する」
ご参考まで！
カナダ 
