How do I know what size generator to get

I have a north star industrial hot box and need to get a gen for it but don’t know what size to get any suggestions

See what the hot box requires

It says 125 amps on it which is the plug right???

I can never tell if you are asking a question or making a comment. It took 30 seconds of searching to find the answer that you needed. Give the Internet a shot. Tons of info there.