execution environment; runtime environment
Computing term for the hardware and software configuration in which a program runs.
This program only runs in a specific execution environment.
It took time to set up the runtime environment.
開発環境 is a development environment (tools for writing code), while 実行環境 is the environment where the finished program actually runs.
Compound of 実行 (execution) and 環境 (environment). A straightforward modern technical term.