do some reading and come back with more specific questions 😉

I’m not quite sure what you need to know, but genotype is the genetic make-up of a person and the phenotype is the physical expression of the genes (i.e. tall, red hair). Heredity and variation is a pretty wide subject, so you might want to ask more specific questions (repeating the last post). Have you read about Gregor Mendel’s experiments with peas?