The part attached to the tap and item 1 seem to be two halves of a vacuum breaker (anti-siphon device).
http://www.oras.com/en/professional/pro ... ode=261032
There should be a third (I think hard plastic or possibly ceramic) part between them that controls the water flow. When there is pressure from above, it should block the middle channel that goes to the four holes leading out to the sides of item 1, and only allow water to flow down the other four vertical holes to the bottom connector of item 1.But if water flows upwards from the bottom connector, the third part should move up to block the top connector and allow flow only between the side holes and the bottom connector.
In Finnish, the proper name for it is
takaisinimusuoja or just
imusuoja but even some plumbers may talk about
tyhjöventtiili (old name I guess?), or
takaiskuventtiili which is a slightly different thing.
The purpose is: if water pressure in the pipes is lost for any reason while your washing machine is running, it might be possible for some water that's already entered into your washing machine to get siphoned back into the pipes. This is unsanitary and disgusting, as Finnish tap water should generally be good to drink as-is as a matter of course.
The vacuum breaker should stop that from happening, and let air into the washing machine hose to stop the siphon instead.
Modern washing machines should be all designed so that dirty/detergented water cannot flow back into the input pipe, so a dedicated vacuum breaker is actually an extra safety measure to protect from old and/or totally flooded or otherwise seriously malfunctioning washing machines.
