olemus
Wiktionary:
7 (computing) the carrying out of an instruction, program or program segment by a computer

ISO/IEC 2382:
protsess, millega arvuti teeb teoks programmi käsu(d)
= the process of carrying out an instruction or the instructions of a computer program by a computer

execution and control -- täitmine ja ohje
execution environment -- täitmiskeskkond
execution time -- täitmisaeg