Below are some examples of questions to ask your beta readers. Delete any you feel aren't help and/or add your own.

What were your overall feelings and opinions on the story?
Did you find the story interesting?
Were the characters relatable and well-developed?
Who was your favorite character and why?
Which character did you hate the most and why?
Did the story keep your interest from the beginning to the end?
Were there parts where you felt the story was too slow or too fast?
Were you satisfied with the ending of the story? Why or Why not?
Could you vividly imagine the settings described in the story?
Were the world-building elements consistent and immersive?
Did the dialogue feel natural and authentic?
Were the themes of the story clear to you?
Did you pick up on any underlying messages or symbolism?
Were there any noticeable issues with punctuation, grammar, or spelling?
Were there parts of the text that were confusing or hard to understand?
Were there any surprises or twists you enjoyed?
What specific areas do you think could be improved?
Do you have any suggestions for enhancing certain scenes, characters, or plot points?
Can you think of any other books or stories that are similar to this one?
How would you compare this story to other works in the same genre?
Were you left with any lingering questions or unresolved feelings?