Teachers are supposed to be our allies, and they often are. However, sometimes they can be intimidating. Failure is okay - it's how we learn! But, any student needs to feel comfortable asking for help when they are stuck. However, often students don't know how to ask for help. Why is that?
Very often a student has asked for help in the past, but it didn't work out. Sometimes teachers simply repeat the instruction (the same instruction that the student didn't get the first time). That won't be effective! Sometimes students find it embarrassing to ask for help when the rest of the class has moved on. Students will learn to eventually fear failure so they will angle themselves out of trying.
The best thing a student can do is learn how to self-advocate and ask open-ended questions. Are you a tactile learner? Are you a oral learner? A teacher with a class of 30 students won't know this about you unless you let them know your learning styles and preferences. They aren't mind readers!
Did the teacher try to re-teach the content in the same way that didn't make sense the first time? Don't shut down - instead let them know! You can say, "can you try explaining that in a different way?"
You won't get along with 100% of people you meet in life. It's possible and very likely that you will have teachers that you simply don't connect with. You should feel empowered to ask the teacher if they can recommend someone else to try to explain the concepts.
This all comes down to self-advocacy. With so many students, teachers may not always be keenly aware to the lesson-level needs of their entire classroom. Students need to get to a place where they feel comfortable talking about their strengths and their weaknesses, and most importantly, asking for external help. You will have to be the one that speaks up and tells them.
For more on this, check out this episode from Attention Talk Radio.