What is meant by the statement "a niche is a species' way of life?

It means the relational position of a species and/or population in an ecosystem. A niche includes more than what an organism eats or where it lives.

an organism's phenotype is the  form of a trait  that it  displays. for  flowercolor, a pea  plant  can  display  a phenotype of purple or white flowers. an organism's  genotype  is the alleles of a gene it contains. based on his data, mendel concluded that a phenotype can be  determined  by more than one  genotype.