It's a virtual computer that can run programs created as boolean logic circuits
What's cool about it is, these programs can be embedded into bitcoin addresses, so that anyone who sends money to a bitvm address can only spend it if they correctly run the program embedded into the address
And the program can theoretically be anything -- it could be Photoshop, or Doom, or a copy of the ethereum virtual machine, or anything. If a computer can run it, you can in theory convert it to work in bitvm, and then basically pay someone to run that program, or get them to put up some money as a pledge that they *will* run the program correctly, then take their money if they don't