In simple terms, what is the voting rights bill the House just passed about? ?

It's about making it possible to steal elections because it legalizes or requires all of the things that make that easier.  Things like: not requiring voter registration rolls to be purged, online registration with no required, no ID  required to vote, requiring ballots mailed to every registered voter, ballot harvesting, no requirement that signature on ballot match signature on registration, votes counted if received after deadline, etc, etc.

The Democratic Party cannot win if an election is free and fair. They are trying to ensure that allowing fraud is the law of the land.