This 555 timer is wired in mono-stable mode, with a 1 Hz pulse on the trigger. the output is driving a double-throw relay, with two motors and two LEDs. R1 and C1 give the 555 timer an output of 500mHz. The two resistors in series with the motors / LEDs provide an easy spin up for the motors and also act as the in-series resistance for the LEDs. These resistors are 100 ohms.