The term fiscal means राजकोषीय or राजवित्तीय but राजकोषीय is more prevalent .

The term devolution means उत्तराधिकार के रूप में हस्तांतरण, अधिकार या प्राधिकार का अंतरण या न्यागमन

So, the term fiscal devolution means राजकोषीय अंतरण/हस्तांतरण, राजवित्तीय अंतरण/हस्तांतरण, वित्तीय अंतरण/हस्तांतरण

A passing down or descent through successive stages of time or a process.
2. Transference, as of rights or qualities, to a successor.
3. Delegation of authority or duties to a subordinate or substitute.
4. A transfer of powers from a central government to local units.

fiscal devolution means transfer of power or authority from a central body to smaller one.(plz reffer oxford dictionary)