Original: The penis in most male Coleoidea is a long and muscular end of the gonoduct used to transfer spermatophores to a modified arm called a hectocotylus.
Simplified: The penis in most male Coleoidea is a long and muscular end of the gonoduct (tube for sperms) used to transfer spermatophores (sperm packages) to a modified arm called a hectocotylus.