If we see that flip-flop is a mod-2 counter with starting count as 0. If we connect J & K to HIGH and supply clock to the flip-flop, we’ll see that flip-flop would count pulses 0, then 1 and as it is a MOD-2 counter so it’ll reset and again count from 0.
And the output is as:
Also note that output pulse is of half the original frequency of the clock.
Hence we can say that flip-flop acts as a Divide by 2 circuit.