https://www.pcgamer.com/master-brutal-combat-in-sekiro-shadows-die-twice/

Death comes quickly in the brutal world of Sekiro. The Dark Souls creators have built a combat system far more decisive and punishing than their previous games. It doesn’t matter who you are in this dark fantasy imagining of Sengoku Japan, it only takes a few strikes with a samurai sword to end you.

In Sekiro, posture matters almost as much as your health bar. Repeated strikes grow a yellow bar at the top of the screen. Once the bar fills up the enemy is open, and you can destroy them instantly with a Deathblow finisher.