Consent.
"The proposed law would require ISPs as well as social media giants to get user consent before collecting and selling their data."
They already do. But the bit where you actually give them that right it is normally buried on page 12 of some impenetrable set of T&Cs and caveated by them actually saying something like "we MAY transfer your data to 3rd parties to improve your experience blah... blah... blah..." i.e. something entirely different that if do chose to read and refuse would make the service unusable.
What it means at present is that you cannot actually refuse these terms if you want to use and modern services such as internet, apps, mobile phones etc.
And it is only getting worse, with more and more normal retail companies seemingly now wanting my data when I buy something over the counter.