An eagle in golf is when you score two under par on the hole. Example: On a par 4 you score a 2 or on a par 5 you score a 3
two under par
GIR is green(s) in regulation. This means the player hits the green in the number of shots determined as regulation. On a par three it is one shot, par four it is two shots and par five is three shots.
Double bogey is two over par.
A score for one hole that is one under par is an, "Eagle".
Par is how many shots you are allowed to complete a given hole in. There are par 3s, par 4s and par 5s. In very very rare cases there are par 6s. On a par 3 you are allowed 1 shot in regulation to hit the green, and two putts. On a par 4 you are allowed to hit the green in two shots in regulation and two putts. On a par 5 you are allowed 3 shots to hit the green in regulation and two putts. You don't have to do it that way obviously, but that is how the holes are broken down and pars calculated.
An Eagle in golf is lower than a birdie. A birdie is 1 stoke below par on the hole and an Eagle is 2 strokes below par For example, on a par four, an eagle is two strokes on a par three, an eagle is not used. it is just referred to as a hole in one!
Usually, although for a Par 3 hole, it may be quite short as the idea is to get "on" in one and two putt.
Par is the regulation score for a hole in golf. A player would find the green in regulation, and have two putts, well that is the idea.