Complex sentence: He introduced zeta integrals on arithmetic schemes of dimension two, such as proper regular models of elliptic curves over global fields, and generalized the unramified part of Tate's thesis to its two-dimensional version.
Split into simpler sentences: He introduced zeta integrals on arithmetic schemes of dimension two, such as proper regular models of elliptic curves over global fields. He extended and generalized the unramified part of Tate's thesis in its two-dimensional version.