Every character has a pool of hit points:

Lvl 1 HP: 10 + constitution modifier

On each level up: New HP = Current HP + 2d4 + CON mod + (applicable trait effects)

When a character reaches 0 HP, they are knocked prone, gain the status ‘downed’, and gain the status ‘wounded’. An unconscious character cannot take any actions.

An ally can make a medicine skill check to assist the wounded character. The wounded character recovers 1 HP, the downed status is removed, and they can take actions as normal.

An ally can administer a healing potion or use any form of healing to assist the wounded character. The wounded character recovers with the amount of HP they were healed for, the downed status is removed, and they can take actions as normal.