Visibility Settings

General Visibility

Isolate Face Hides all bones that are not in the face

Face Simple and Face Complex toggle simple and complex face functions

Menu Toggles the floating menus to the left and right of the character

Debug Unhides all DEF, CTRL and MCH bones

IK Visibility

does what it says it does

Second Layer Visibility

displays or hides the second Skin layer in the Viewport or Render