They might get the referrer (i.e. the URL the page the request came from) and information about the browser since it's your PC/phone that actually contacts Google's servers to request the resource. As long as the URL doesn't encode any PII, that will be it.
I'd guess that bigger thing that companies like Google get from hosting resources like fonts etc. is that it provides them yet another, and much broader, market research data point re: what browsers are people using, what fonts/scripts are sites using and so on. So even if you completely avoid Google products/services like Android/Chrome/Chromebook/etc., they'll still get a bit of usage data from both you and the site.
I'd guess that bigger thing that companies like Google get from hosting resources like fonts etc. is that it provides them yet another, and much broader, market research data point re: what browsers are people using, what fonts/scripts are sites using and so on. So even if you completely avoid Google products/services like Android/Chrome/Chromebook/etc., they'll still get a bit of usage data from both you and the site.