Yes, they do. When you set up business hours, the time elapsed on a case during non-business hours is not calculated while measuring the SLA.
For example, if a case is assigned to an agent that is due in 4 hours on a Sunday morning, and the agent is not working on Sundays, then the clock will start ticking only on Monday when the agent’s business hours start. Business hours will also help redirect phone calls to voicemail during non-business hours.
To know more about Business Hours, click here