she mends me= she heals me or that her love heals me and makes me a better person.

It means repair, rebuild mean to put into good order something that is injured, damaged, or defective. mend implies making whole or sound something broken, torn, or injured.

thanks Mariah i completely got it!your explanation was very clear!

It is kind of like saying he/she fixes a person or heals them. The scenario could be in terms of helping someone get over a bad break up or a tough time.