The objective of the Queens Gambit Accepted is to temporarily sacrifice a pawn to gain control over the e5 square
The Queen's Gambit accepted is played when black goes 2...d5 for example:
Here white would have to sacrifice the c-pawn in order to win the game. If not then the game may lead to a draw, and wouldn't be good for white since white has the first move. The only way to not get a draw is by moving 2.c4 for example:
White is sacrificing a pawn, but can also regain with positional advantage with 3.e3 and white will have a nice game and can win (if you play good).
Queen's Gambit declined
The Queens Gambit declined is when white offers white to take the c4 pawn, but instead black refuses to take the c4 pawn and continues developing. The Queens Gambit declined can make sure to control the center a bit, and not let white control the center.