Ive found some conflictinginformation about this online. Some people seem to think this has to do with how difficult it is to rank organically in Google for that keyword, however, its actually a metric to gauge competition in Google Ads for that keyword on Googles Search Network.
So basically, its a scale from 0-100, 0 being very low search advertisercompetition and 100 being very high search advertiser competition.
Heres the math used by Google to calculateCompetition [indexed value]:
Number of ad slots filled / the total number of ad slots available
This is the definitiondirectly from Google:
Competition [indexed value] shows how competitive ad placement is for a keyword, specific to the location and Search Network targeting options that youve selected. The level of competition from 0-100 is determined by the number of ad slots filled divided by the total number of ad slots available. If not enough data is available, youll see a dash [-]