The answer to this depends on the type of class you are taking and when you ask your question.
If you are taking a hybrid, live remote, or flex class, you can ask your instructor during a class session to get an immediate answer.
If you are taking an online class or if you email your instructor outside of scheduled class meetings, the general guideline is 24-48 hours, but many faculty respond sooner than this.
Note:  Instructors are not available 24/7, so if you ask a question late at night or over the weekend, you may not get a response until the next business day.
If you have a question and would like a more immediate response, consider attending your instructor’s office hours or setting up an appointment with them (in-person or virtually) to discuss your questions and get clarification.
Refer to your syllabus for your instructor’s contact information and office hours.