In the circuit shown, you find out how the RESET input is connected.
When you press the pushbutton switch S1, the LEDs LED1 and LED2 are flashing. When you let go of S1, the multivibrator stops and only LED1 is on. This is shown schematically in the illustration.
This circuit is known as a "gated astable multivibrator" and is an important circuit in electronics.
But now you manipulate the switching times...