It's for washing
out with freshwater (from a town water
supply) an outboard engine
The goal is to wash with town water
the residual seawater from the cooling
channels running up the leg of the outboard
, from the propeller
to the engine
proper. Doing so reduces corrosion
and deposits of salt
The green fitting is for a garden hose. The two now-stained beige discs are held, by the wire, against the water intakes at the propeller
end of the leg of the outboard engine.
Generally called, in English
, "flush muffs"; from "flush" as in to flush, to wash away + "muffs" (from looking similar to ear muffs).