If it helps:
the in signal at the top passes through the mixer and can be heard at the out
with the mixer at 0 no wet signal will be mixed into the dry signal passing through the mixer
as you increase the value on the mixer more of the wet signal is added in and can be heard at the out
p.s. the down arrow to the in before the delay is slightly confusing to me, what this means is that you assign the in signal to the beginning of the subchain (the one with the delay in it) as well as assigning the in to the top level chain (the one that contains the mixer).