Teachers often ask if their remarks were understood, but then often no one answers. Take the opportunity to ask! Others in the class will be glad to know that someone asked because they didn’t understand everything either.
If you only realize later during homework or exam preparation that something is unclear to you, then it may take a little more courage to ask again in class. In a positive class climate, this is common and helps teachers better tailor their lessons to the class.
Of course, you can also ask friends or family members.