A timer object times how long an interval occurs between a left inlet bang and right inlet bang.
A pipe object delays a message by some time, 100 milliseconds here. Thus the outlet of pipe will be active 100 millsecond later. The float is passed to a number box and also to bang, to convert float to bang.
Thus the second bang, input to right inlet of timer, is set by pipe and not meant to be set by user.