Average Position is used in Google Search Console and Google Ads.
Average Position is calculated based on the rank (or position) of your site.
An Average Position of 1, would indicate you are ranked in 1st position on Page 1 of Google.
An Average Position of 1.5 would indicate that your site ranks between 1st and 2nd position on Page 1 of Google.
An Average Position of 11 would indicate that your site ranks 11th, i.e. top of Page 2 in Google.