Basically, here's what happened: Congress specifically forbade the FCC from applying common carrier regulation to what the Telecommunications Act of 1996 calls "information services." The FCC has said that broadband Internet access is an information service. As such, the Court ruled, the FCC cannot apply common carrier regulations to them, such as nondiscrimination and no-blocking rules.
What comes next? The FCC will be urged to change its mind as to whether broadband Internet access is an information service, declaring it instead as a "telecommunications service" (which can be, and would be, regulated extensively). Congress could act (stop laughing!) to give the FCC broader authority over information services. And the FCC may appeal this decision, either to the full DC Circuit sitting en banc, or to the Supreme Court.