Direct answer
A shield allows you to block incoming damage. If your timing is perfect, the enemy may also be parried. Be careful though, if you block too many hits you will become staggered. The amount of damage you can block before becoming staggered depends on your maximum health, so if you plan on tanking a lot of damage you should eat food that increases your health. Heavier shields will block more damage but will also slow you down.
Wood Shield · Use
Result
Equip a shield to block attacks. Well-timed blocks can parry; more maximum health lets you withstand more blocking stagger. Wood Shield