Click '+ Availability' and choose '+time off' as the schedule type
Add a description eg. "Lunch"
Set the time that you are not available eg. 12:00 - 13:00
Set the repeats: If your lunch break is from 12:00 PM to 1:00 PM daily, for example, set this time and schedule it to repeat every day of the week.
Select team members: If this break applies to the entire team, select 'any resource'. But, if each team member has different schedules, you'll need to set 'time off' individually. Simply repeat this process for each member.