Molang

Molang is a simple expression-based language designed for fast, data-driven calculation of values at run-time, and with a direct connection to in-game values and systems. It is used in Bedrock Edition's Add-on system with it's purpose being enabling low-level systems like animation to support flexible data-driven behavior for both internal and external creators, while staying highly performant.

Mojang provides official documentation Molang Documentation which goes into details of how the language works and where it's used.