Wave
Tony.... go to this site: h**p://www.boatnorth.com/sailing/index.html
I found simple images that should help you understand.
1st image: shows just the main sail. The mast is the tall pole in the middle.
2nd image: shows both the main sail and the jib. The Jib is the smaller triangle in the front of the boat. In this image, the jib is shown on the right.
sail forward of the main sail/mast
Means that the small JIB sail is in front of the mast (tall pole in center) like shown in 2nd image.
Don't know anything about sailing/boats but am good about finding things.