My dentist told me to take liquid amoxicillin amox. What will it do to me?

Infection Control. Either treat an existing infection or prevent one from starting , are the goals here.
Infection. Amoxicillin is an antibiotic. So it will kill bacteria. As with all broad spectrum antibiotics it can also give you diarrhea. If you have an allergy to penicillin it can give you a rash or full blown allergic reaction.
See below. Why are you taking this? This is an antibiotic so i would say that it will reduce ore get rid of any infection you have that will respond to this drug.