If it says 3 phase, then it is. The 208v and 440v are the numbers to confirm it. 208/440 have always turned out to be 3 phase on a motor, when I have seen them, and a home user is very unlikely to have either of those voltages even if the motor would have been single phase.
That is the first motor I have seen with 220v on it, so I can understand your confusion.
I am not sure of what brand the compressor is. Your description appears to be just for the motor, when I did a google search. I didn't see compressor pumps pop up.
If you get a good 5hp motor and this project doesn't work out, you will be set to find another old quality pump, as long as you don't mind spending the money. It seems like 3 phase motors are a dime a dozen and single phase not so much, so good luck with finding a 5hp single phase motor for a great price. It could happen but you might just end up going with a new one.
