The phrase "to fix this site" means to correct or repair any issues or problems that the website might have in order to make it work properly or be more effective. Full definition
«Today's announcement is the first step» to finally fixing the site. (politics.co.uk)
Just visit the Stitch Fix site and click the «Gift Card» banner to snag one! (stillbeingmolly.com)
And while most North Korean missiles are fired from fixed sites, North Korea has developed solid - fueled missiles that can launch from anywhere at virtually any time. (businessinsider.com)