\time is a parameter that TeX initiates to the number of minutes that have completed in the current day. TeX sets this parameter once upon start-up. If, for example, TeX starts at 10:32:45am, then \time would be set to 60*10+32=632, dropping the 45 seconds. This parameter may be changed to <integer> with either of the two equivalent forms above.
Recall that the command \number will typeset the decimal representation of whatever follows it, and TeX started at, say, 10:32:04am then
will typeset 632, if the \time parameter has not be redefined since TeX started.
will typeset -45.