A genotype is the set/combination of genes.
Say something had two genes for being short. The genes involved in it (call them "n") would be in the genotype. For example, if the genes were "nn", its genotpype would be "nn" for that trait.
The phenotype is the outward expressed of the genes. So, if the genotype cause this creature to be short, then its shortness would be its phenotype.