◾Lean

Leaning is the ability of a player character to lean to the left or right while moving or standing still. This is done by procedurally animating the character's upper body

Leaning is often used in first person shooter games to allow players to look around corners without exposing their whole body to enemy attack by reducing their visible profile. Here you can set how much to rotate each spine bone to the left and right, while the neck bone is the value to rotate the opposite.