Can we play "A Way Out" on single PS4?
Solution 1:
Yes, you can.
"Couch co-op" means that multiple players can play on the same console. It's named after the couch that people sit in when playing games together.
There's also "split screen", which is essentially a technique where the screen is split (hence the name) to show content for each of the players.
Either of those terms alone already explicitly indicate that only 1 console is needed for all players. In this case both terms are used together, so there should be absolutely no room for doubt.