Potions
You have just triggered a trap. Your Warrior has little defense against Traps. The Rogue role, however, can find, disarm, and even place traps.
The trap did significant damage to your character's Hit Points (HP). In addition, you have just spotted some hostile Orcs, putting you in a bad spot!
Luckily, a potion of healing has been added to your inventory. Open your inventory, right click on the potion to open the menu, and select "Drink" to drink the potion.