An example might help in understanding just what these mean. Let's say that you depositR$250 to a sportsbook that is offering a 50% bonus with a 5x rollover. This means that you'll haveR$375 to bet with, but can't withdraw the bonus money until you've placedR$1,875 ((250+125)x5) in bets.
Yes, of course, sportsbook bonuses are worth it! Some sites offer reward bets that usually range fromR$500 toR$5,000. That means if you betR$5,000 on a single wager and win, you're making bank. If your wager ends up losing, the sportsbook gives you a site credit or a bonus bet as a second chance.