I've never played it but I've watched it before. Ever play bocce (kinda like lawn bowling) cause it's kinda like that.
You slide this rock down an alley of sorts and attempt to get it as close to the center of the target as possible. However, you take turns with your opponents, so while you may get the exact center of the target, they could knock you out of there with their turn. Also, people take advantages of geometry to hit multiple targets at the same time, like if you've played pool and bounced a ball into others to knock them in.
I believe the scoring comes down to how many stones you have within the target area at the end, but it's been years since I've watched it, so I don't know for sure.