feeding another circuit a start signal (initializer) with d-latch (1,0,0,0,0...)
A D-Latch copies its input to its output. The latch in your drawing has an inverter connected to its output (shown as just a bubble). Since its input is always 1, it's output will always be 0. 

Except for the note "assumes latch is initialized to 1". So it's initially 1, and then once it starts getting clock edges, the output is always 0.

Edit:

Incidentally, I would recommend to add one or two more D-flip-flops in series in order to get 2 or 3 periods of initial "1" value at the ouput. This is in case the clock period is not stable when the circuit first powers up, you will be sure the reset signal is correctly distributed all around your circuit.