"this rare complete original 1984 MacFORTH Level 2 collector set!"???

collector set?!?

It's a freakin' box of software! Not a limited-edition collectible plate!

As for what it is. It's a programming language. I was happy to never have to learn FORTH. FORTRAN was bad enough. (Although from what I recall, FORTH is a fairly simple yet powerful language for mathematical use, just as FORTRAN is simple yet powerful for engineering use.)