Hold Current Keys sets keys for all animated attributes of a selected object at the current time. This menu item is most useful with Auto Key because Auto Key sets keys only for attributes that change value. For more information, see To hold Current Keys with Auto Key.
For example, suppose you are animating a character’s walk cycle. When a foot is on the ground, its position must be held for a number of frames. If you were to use Auto Key alone, a value must change before a key can be set. Hold Current Keys sets a key for the foot even though the values do not change.