TIME$ is a read-only system variable which gives the time of day in a string format "hh:mm:ss". The 24-hour system is used, so just after 3:41pm might look like "15:41:07". Midnight is "00:00:00".
The command TMREAD goes with this system variable; TMREAD(TIME$),variableH,variableM,variableS will set the three variables to the hours, minutes, and seconds of the current time.
See also DATE$ (System Variable).