Some people get lots of them, and others do not. It may be for an interior or other accommodations, may be for a BOGO, may be $$ off or may be for what they call 'special casino pricing'.
This offer may also include a value you can apply to a cruise not listed. The next is a promotion free cruise award emailed/mailed by the casino for a variety of sailings, or maybe just one sailing. I cannot offer any other info on this type of free cruise as we have never obtained the necessary points. Some number of points ON ONE CRUISE gets you a certificate for a specific type of accommodations and on specific sailings. One is a few cruise certificate by gambling on ONE cruise. There are several types of free cruises offered by the casino, and some have different rules.