Typically on one side of the plastic body will be a diagram of how to connect it.
Obviously it's not the side that you took a picture of.
This is what I found when I did a search for BV 5763 Solenoid Valve.
http://www.pneumaticdepot.com/pdf/stc/2S025-050.pdf
It looks like the one you have.
To connect DIN Coil:
1. Remove the Philip screw from the plastic housing and unplug it from the DIN Coil.
2. From the screw opening, push the terminal blockout from the plastic housing.
3. Note the 1, 2 and ground markings on underside of DIN Enclosure.
4. For DC DIN Coil, connect 1 to Positive, 2 to Negative.
5. For AC DIN Coil, connect 1 to Hot wire, 2 to Neutral and if required connect.
I'm assuming that they mean if required connect ground.