A Slack status is an indicator of whether you're open to chat, and/or when people might expect you to be. For instance, if you're open and free to chat, you don't have to set a status. You might want to consider adding the Google Calendar Slack App in order to automatically have your status updated when you're in a meeting.
If you're taking a short break or on vacation, we have options for those too, but you can always set a custom status as well. See the prepopulated options here:
Turn on Do Not Disturb when...
You would otherwise be free but need to be heads-down on a project
If you're in a meeting where you will be presenting
If you're on vacation
To turn on Do Not Disturb, simply type
/dnd [length of time] into any message box. It will not be seen by other participants.