The present perfect expresses a long span from past to present.
Literal
Present-perfect [topic-は], past~present [called-という] long span [object-を] express thing [copula-です].
スパン is a loanword from English 'span.' 過去~現在 uses the wave dash to indicate a range. ものです here means 'it is something that / it is a thing that' — defining what the present perfect does.