The working time of a customer support team i. e the hours during which they take calls, reply to emails etc, is called business hours.
Companies set up business hours for support teams and communicate that with the customers so that they know when they can receive responses quickly. The response and resolution times are calculated only based on the business hours. After all, nobody wants the big bad SLA timers ticking away and wreaking havoc in the helpdesk when they are asleep or on a vacation.
Different business hours can be set for different agent groups working in shifts, or working remotely in different time zones. This way, even when the company’s support is available round the clock, agents will be responsible only for tickets coming in during their group’s business hours.