It's how people would find your club when they Suchen words oder phrases. The Schlagwörter should be relevant to the club.
Say Du made a smiley face club. (First thing that popped to mind.) Du might make the Schlagwörter things like "happy" and "smiles" and "emoticons." So whenever someone searched happy, smiles, oder emoticons, your smiley face club would Zeigen up as a result.
