At least one side is always outputting a signal. If the opposite side receives a pulse, the latch flips and starts outputing on that side and the original output side is now the new input. Also known as a 1-bit counter. Useful for turning a single pulse into a continuous signal.
Said another way, when the input receives a signal, that same input becomes an output for the signal as well. For example, a Timer connected to an input that is off will rotate for its timed duration and pulse a signal, activating the RS Latch. The path the signal used will now remain on (as well as its corresponding output) because that input became an output, which supplies the Timer with a signal that will stop it. To have the Timer start again requires a signal to the other input of the RS Latch. So, to have the Timer continue working without interruption, a Repeater can be used (which will only allow a one-way signal) placed facing away from the Timer. The picture (right) shows a RS Latch connected to two Timers to create a timed delay. The one on the right has a Repeater/Diode in the path to prevent feedback to the Timer.
If you turn on both inputs at the same time this device will burn out.