I started using a second PC monitor many years ago. At that time my PC was a big cream-colored box, and the two monitors were bulky, heavy, expensive TV-type things.
But the space, trouble and expensive were worth it. I still say today, adding a second is the biggest productivity-increaser you can do.
Nowadays, most of us are working on a laptop, and that makes it far easier to add a second monitor! You just plug it in to the HDMI connector on your laptop, and Windows will find it. Go into your Display settings and you’ll find the place to tell Windows to “Extend my display onto this monitor.” You have to tell Windows where the monitor physically is (mine is to the right and somewhat higher than the laptop), so that dragging windows from one to the other feels natural for you.
Once you have your monitor working, you might also think about mounting it on the wall in front of you. As I’ve gone into literally hundreds of home and office workspaces over the years, maybe 1 out of 20 has the monitor up at eye level where it belongs. Once that required unsightly plastic stackers (I piled up phone books, back when they existed) to raise the monitor, but modern flat-panel screens are very easy to mount on your wall.
(HINT: if you’re doing this for the first time, you might want to get a piece of wood and stand it up between your desk and the wall. Mount your monitor to THAT first; it’s much easier to work with wood screws and experiment with the height to get it just right. Once you know where you want the monitor, you can take it off the board and then drill right thru the board to put your holes in the wall.)