Your hours decide when your booking page offers times. Every account starts on a standard week, so you can open your page without touching them; press I'm happy with it on the Setup Guide to say so, or set your own under Settings → Hours.
The weekly pattern
Open and close times for each day, and the days you're shut. This is the business's week: the outer edge of when anyone can be booked. A customer never sees a time outside it.
Each person's hours
Inside that week, each team member has their own days and times, on their Team profile. Someone who works Tuesday to Saturday only shows times on those days, even if the business is open Monday. A person's hours can never widen the business's; they can only narrow them. See Add your team.
For rotating weeks and one-off changes, see Rosters, rotating weeks and one-off changes.
Days you're closed
Public holidays and your own closed dates come out of the calendar in one place; see Closed dates and public holidays. A single person's holiday or sick day is time away, which takes them out without closing the business.
Changing hours later
A change applies from now on. Anything already booked stays where it is, even if it now sits outside the new hours; move or cancel it yourself if you need to. If a time you expect isn't showing on your page, this article walks through why.