What are Business Hours?

Hi Suraj

Business Hours

Specifies the business hours of your support organization. Escalation rules are run only during these hours.
If business hours are associated with any Holiday records, then business hours and escalation rules associated with business hours are suspended during the dates and times specified as holidays.

For more infohttps://developer.salesforce.com/docs/atlas.en-us.api.meta/api/sforce_api_objects_businesshours.htm

Hope it may help you