I spend a fair amount of time looking at numbers on displays. You're definitely doing the right thing here, I've never regretted buying a good monitor, it's the most important part of the computer for a lot of people.
Now since you're a noob, let's just make sure you understand the difference between resolution and size. Higher res allows more stuff on the screen than an equal-sized monitor of a lower resolution. That's basic and you may well know it already, but gotta mention that first.
What 4k does is make things clearer. Basically instead of one pixel worth of detail, they use 4 pixels in about the same space. Smoother text, images, like your iPhone or phone. Right? Right. So with a standard 1920x1080 monitor (same as most TVs), you're counting pixels horizontal by vertical for a standard HD screen to get that. With a 4k in normal use, there are double the amount of pixels in the same space, for example 3840x2160 - so you still see the same thing on the screen, just more defined. You don't need that, but obviously it's desirable.
So first, you want to figure out how much resolution you're looking for, and then how big it is. You can buy a 1080 display in anything from a 20" monitor to a 60" TV if you want. You need to consider how close it's going to be to your face and what looks right.
IPS, TN, etc are talking about the panels. Some are better than others in appearance, color representation, some are more suitable to quicker refresh rates for gamers. For workstation purposes really any will do, but I find IPS less harsh and with more vibrant colors than cheaper TNs. But there are lots of types of IPS and options.
My advice for a standard work monitor you use a lot, start by checking out 2560x1440 (aka QHD) displays with IPS panels. You can fit a lot on the screen and they generally look better than your run-of-the-mill super-cheap things that Mom buys with her Dell. What size - well, you have to go out and sit in front of them.
With my desk, I found 25" displays work best, but many people prefer the more typical 27" display size for that resolution.
That res is also the sweeter spot between price and performance. Here's an idea how how many prices and sizes there are for that res:
https://www.newegg.com/Product/Produ...NG&PageSize=36
Finally, I'd probably make sure it has both HDMI and Displayport for maximum connectivity. A good display can go for a long time and I've found it worthwhile to be forward looking with them.