Because a delivered bowl swerves to one side (the bias), you cannot deliver bowl straight along the objective line. The objective in is the straight line from the mat to the jack or the spot where the bowl should come to rest.
Instead the bowl should be delivered at angle to the objective line. The angled line along which you have to deliver the bowl to come to rest near the jack, or other spot, is called the aiming line or delivery line. The aiming line varies according to conditions on the green and the weather. And, of course, the build of your particular model of bowl.
Your coach, or experienced players, may advise you how to find your aiming line verbally or by putting a foot in a certain position, but you yourself should, by trial and error and experience, determine the aiming line which suits your play on your particular rink of play. There is an aiming line for the forehand (the right) and the backhand (the left).
How do you find your aiming point in bowls?
Players often ask where they should look when delivering a bowl. You will get different answers from different experienced players. Personally, I have tried out advice from various champion bowlers.
The most useful answer is: your aiming point should be along your aiming line straight opposite the jack. This helps greatly in achieving the correct weight i.e. not playing past the jack or ending up short of the jack.