Scripting is programmed level-specific behaviour that is currently defined by inputting command lines in the level files' "script" section. A full documentation of Scripting can be found here.
Scripting has four main components: occurrence, triggers, events and variables. Occurence tell the game if the script is allowed to run multiple times or just one time, triggers tell the game when the script is allowed to run, events tell the game what should happen and variables are used to keep track of what's happening in the level.
The Level Editor can show the Row, Column and Tile ID you are currently hovering by clicking the Script Interface button. There is also a handy log that tells you exactly what has occured and if the code got any errors.