Capital Lock Indicator - Asus A53TK Manual

Capital Lock Indicator

Indicates that capital lock [Caps Lock] is activated when lighted.
Capital lock allows some of the keyboard letters to type using
capitalized letters (e.g. A, B, C). When the capital lock light is OFF,
the typed letters will be in the lower case form (e.g. a,b,c).
52 Notebook PC User Manual