Luke: come to point o five, we'll cover for you
What does that mean for example?
They're providing Luke with information about where they want him to fly so that they can provide covering fire or shoot down anything following him.
The "point oh-five" is the specific direction and from the (minimal) searching I've done I think it's just babble to fill out the script.
Pilots use clock numerals to give relative directions "9 O'clock high" for example would mean on my left and above me. Of course Star Wars pilots don't necessarily have a 12 hour clock as a frame of reference and with a (potentially, but rarely used) fully 3-Dimensional battleground to play in a system that works on Earth isn't ideal for a Star Wars space battle.