Of what is the first filial generation a result?

The first filial ($\text{F"_1}$) generation is the result of a cross between the parental ($\text{P}$) generation. In Mendel's study of heredity in pea plants, the parental generation in the cross would be two true-breeding (homozygous) plants that differ in a particular trait; for example tall or short plants, and purple or white flowers.The purpose of the cross is to analyze the pattern of inheritance for a particular trait.