The 'Meaningless Content' category is defined, by Fortinet as "URLs that cannot be definitively categorized due to lack of or ambiguous content".
I'm assuming that your Web Filter Profile is set to block sites categorized as such.
A quick bit of research indicates that this site is part of the Google Cloud infrastructure.
My first thought in relation to this is to let the firewall do its job and continue to block the site if you want to err on the side of caution.
However, if users are being adversely affected and moaning about it, you could always create a 'Web Rating Override' in Secuity Profiles > Web Rating Overrides and re-categorize the URL to a category that is permitted by your Web Filter Profile.
Hope this helps.