There's critical race theory in the way lawyers use it to show the systemic racism within the USA and the US Justice System. However, what the Republicans are trying to ban is history. They don't want things like Juneteenth and all the Un-white-washed history to be taught.

Critical Race Theory is basically just acknowledging that systemic racism exists in all branches of governments and they want to undo that by teaching. Part of that teaching would be informing united states citizens of our racist history... Not just slavery and civil rights but everything that still goes on.

Take into account the way the Supreme Court just upheld Arizona Voting rights that would unfairly impact poor and people of color. Critical Race theory would teach this in schools.

Lawyers use it differently than they'd teach it in school but it's all just acknowledging the racist history of the country. Many people also take issue with this because some of that history would discuss Trumps rise to president and The GOP does take issue with that.