By default, Appointlet autodetects your customers time zone while booking. What this means is that your customers will view your availability in their own time zone so they'll be able to book you without worrying about translating times.
However, if you’re only accepting bookings from people in the same time zone as you, you should lock your booking page time zone to yours. This will simplify the booking process for your customers.
To set this up, log in and click "Settings" on the top left:
In the dialog that opens, set the "Booking Page Time Zone" to "Locked" and specify the time zone which the booking page should be locked to.
Now when your customers book, they'll be able to pick a time without any second thoughts: