Take a look at the circuit shown. The resistors R2 and R5 form the coupling elements.
If you connect the battery, one of the two LEDs lights up. The other LED remains dark. As long as you are not touching the push-button switches, it stays that way. The state is stable.
By pressing the push-button switches R and S you are able to alternately switch the LEDs on and off. The second state is also stable! Hence the term bistable multivibrator.
This circuit is also known under the name of Flip-Flop or RS Latch. Here R stands for "RESET" and S for "SET".
But how does the bistable multivibrator works? This you see in the next experiment.