If you got a 91 in an honors geometry semester exam your freshman year will it hurt chances of getting into good college?

A 91 in an honors geometry semester exam is a very good grade! It's unlikely to hurt your chances of getting into a good college. Colleges look at your overall academic record, not just one grade. They consider your GPA, the rigor of your course load (taking honors is a positive!), trend in grades over time, standardized test scores (SAT/ACT), extracurricular activities, essays, letters of recommendation, and more. One slightly lower grade in a single class, especially freshman year, won't significantly impact your application, particularly if the rest of your academic record is strong.