This is a simple circuit from tutorials. It could be used to place a delay between the closing of the switch shown in the figure and the "ON->OFF" signal on the comparator output. This is used, for example, to place a delay between switching on an amplifier and the turning on of a loudspeaker - to prevent the nasty "thump" or "crack" as the power to the amplifier "hits" the speaker. With the delay, any settling-down in the amplifier's power supply is over by the time the speaker is switched in - typically after a few seconds.
Basics of Electronics ... a "Toybox" by Alan Murray, University of Edinburgh is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.