A point spread is a handicap set by bookmakers to make a game more even from a betting perspective. The favorite "gives" points, the underdog "gets" points.
If the Lakers are -5.5 against the Knicks, a bet on the Lakers wins only if they win by 6 or more. A bet on the Knicks at +5.5 wins if the Knicks lose by 5 or fewer, or win outright.
The .5 in a spread (called a "hook") prevents pushes. A spread of -5.5 can only result in a win or a loss — never a push. Finding a spread at -5 instead of -5.5 can be the difference between a win and a push.
oddstatus compares spreads across 9 bookmakers. A half-point difference — available at one book but not another — can flip a loss into a push or a push into a win. Over a season, this adds up significantly.