This 5K monitor competes with my Apple Studio Display (and it's much cheaper)
The Asus ProArt PA27 has an impressive picture with 5K resolution and a vibrant color palette, making it one of the better choices at this level for Windows users.
“If you're listening to amazing gear through terrible monitors, you've wasted your cash”: Why monitors are the most important part of your studio
On a very broad level, monitoring your music is simply listening to it and analysing it for ways in which it can be improved.