Gene pool.
Think of it like this. Humans have tons of genes. Imagine taking just one of those genes between your fingers (if you could - they’re too small in reality) and focusing on just one location or locus of that gene. We would see 2 copies of that gene and each copy is called an allele. If they’re the same, they are homo-zygous. If they are different, they are hetero-zygous. NOW the important part regarding a gene pool. If we took the same gene from a population or large group of humans and identified 20 alleles at that location/locus, then those 20 alleles would make up the gene pool for that locus/location. Take that a little further, and count ALL alleles at ALL locations or loci (plural for locus) and you get the FULL gene pool for the species.
