How do we give directions in space? If I'm on a life boat, in the middle of the ocean, radioing another ship to come pick me up - I'd say something like "I'm 40 kilometers directly east of you."

In space, it's not that easy. How do you give a direction?
You need to define an agreed standard for orientation of axis and origin.

What co-ordinate system you choose as a standard depends on your purpose.

Here are some examples and links : Celestial coordinate systems.

Typical reference points are defined using very distant objects whose position can be measured accurately ( typically quasars ).