If team A serves the ball and it touches the ground on their side after team B returns their serve, then no points are awarded and team B gets a chance to serve.
Points can usually only be scored on your team’s serve, but there are alternate rules that allow for scoring whenever the ball hits the ground on either side. Games are usually played to 25 points, and sets of 3 games are often played to see who wins the best out of 3. It is pretty similar in this way to tennis or badminton.