Level Condition is a feature that enable to compare condition in a level order like:
if(con1 && (con2 || con3) || (con4 && (con5 || con6))))
imagine how to make like that using Validation, the Level feature handle it.
To enable level condition : right click in validation header and select Use Level.
Now level condition are able to use. To use it click on the left or right button on the pic below:
every you increase level the button will have spacing on left depend on the level.