Angle on the bow is nothing more than your heading as reported from the target. It works the same way as German headings, always an angle from zero (straight ahead of the target) to 180 (straight back of the target) and is reported either starboard (recht) or port (links). You want ze picture?
Here's a nice MoBo plot. You can see OwnShip to the left heading north. I don't remember what the impact point is so you can ignore that.
But off to the right you can see our target 4400 yards away or so with the AoB compass rose on it. Note that the bearing of our ship from the target is 66º starboard. That is the Angle on the Bow. Simple, no? Just needs explaining properly.
It's just like explaining to a newbie how to operate an astronomical telescope. At first they are all confused. "Everything is backward and upside-down. How can I learn this crazy thing?" But when I explain to them that all they have to do is move the telescope the direction they want the object to move. If they want the object to move up, they move the scope up. They suddenly forget everything is inverted and in ten seconds are pointing as if they had been doing it all their lives. Everything is point of view!
And Captain Scurvy's Angle on the Bow and Speed Calculator--simply the best!