Suppose that a golf course is meant to be played in 72 strokes, by very good players.
But you are not a professional player, and in such a course, you are expecting to complete using 80 strokes. The difference between 72 and 80 is the handicap, in that case, that would be 8.
With the handicap, the player with a 8 handicap could play against a better player with, say, a handicap of 4. This means that the player with a 8 handicap who plays the round in 79 strokes would win against a player with a 4 handicap who plays the same course in 76.
As for Trump claimed 4 handicap, that is one more lie from Trump. Trump is a known cheater.
Hey, John F the ignorant:
A USGA handicap is calculated with a specific arithmetic formula that approximates how many strokes above or below par a player might be able to play, based on the ten best scores of their last twenty rounds.
Notice the presence of the word "par"?
How do you sound, talking through your hat?