You must have been in communication with an American just lately. The expression most likely relates to the NCAA (National College Athletic Association) basketball tournament that is going on right now. A "bracket" is a layout on a sheet of paper of all the games that will be played, showing who will play who, and who will play the winner of a certain game. When a team loses they are "out" of the tournament-- they play no more. There are four locations that games are played at to begin the tournament. That decreases to two locations, and finally, for what is called the "Final Four" there is just one location. The layout of the "bracket" on paper usually has two of the original locations on each side of the page and the Final Four in the middle. If you "have" or "play" or "make" a bracket it means that you wrote in your guesses of who will win each game for the whole tournament before any games are played. The idea is to get more winners than other people who are doing the same thing. Usually it is for some amount of money, but sometimes it is just for fun. If you "bust" your bracket it means that you have had so many losses in the lower rounds of the tournament that you have no chance left to win.