A creature is Resting recover.

This is done by hitting the Rest button in the character sheet within a campaign.

A Long Rest is a period of extended downtime— at least 8 hours long—available to any creature. During a Long Rest, you Slumberwave for at least 6 hours and perform no more than 2 hours of light activity, such as reading, talking, eating, or standing watch, for a total of 8 hours.

For each hour you gain a stack of Rested.

Entering combat, ends the Resting status effect, and resets the Rested stack by 1, or 1 hour equivalents worth a Rest. When combat is over you may Rest again.

At the end of the 7th Rested hour you gain the benefits of a Full Rest, and gain the status of Fully Rested.

A Resting creature is typically considered Prone, and Sleeping. These are automatically applied if you do GM does hour by hour Resting.

If you are wearing medium or heavy armor, when a Long Rest completes you automatically become Exhausted, unless you have enchantments or Feats to prevent this.

The GM in the campaign screen can also do a summation Long Rest, which will skip the time forward 8 hours and give the benefits of a Long Rest to the party.