Actor category allows you to do few fast manipulations with actors.
Toggle Selectable – toggles actor or component selectable state. Select actor or component in editor viewport or in world outliner and press the button.
Attach – attach actors to the last selected actor. Children inherit parent mobility.
Move Relative – move selected actors in local space.
Rotate Relative – rotate selected actors in local space.
Scale Relative – scale selected actors in local space.