How do you do that actually the three monitors together?

I'm currently thinking about whether I zulege three monitors that I then hang on the wall and connect with my ps4 and my PC only I have no idea how

Cable to TV, cable to PC - done - repeat until enough screens are connected, or the connections go out.

How you want to connect 3 TV's to a PS, however, is a mystery to me.

By simply connecting three monitors to your PC.
That's why your graphics card has so many outputs.
As it looks at a ps4, I do not know. It may support only one monitor.

Usually by connecting them directly (your graphics card has several outputs), some monitors also support daisy chain via DP (ie the monitor then usually have a miniDP output and you can simply switch several monitors in a row, then you only need to address one of them ).

Come on the monitors and your graphics card. You could, for example, 2 DisplayPort cable from your PC to each 2 monitors and 1 HDMI from your PS4 to another monitor. What you can do is to buy an HDMI switch and 1x HDMI of of your PS4 and 1x of your PC on a monitor to use. Of course, not both at the same time.

Well, of course you do not connect the 3 monitors with each other.

Unfortunately, the PS2 has only a composite video output, you can only connect to a monitor that has such a connection (usually yellow RCA socket). Although there's the possibility to distribute the image over 3 (and more) monitors, this requires a video wall processor, but the things are sauteuer and expect HDMI at the entrance. To get your PS2 composite signal (old analog video signal) to an HDMI input, you need something like this: https://www.amazon.de/...07CZB49Y2/

But there are also monitors that still have a composite input. Disadvantage, you must then switch the monitor always between the inputs.

When PC you need just synonymous a graphics card in the PC, which also has three outputs, for example, 2 times DVI + HDMI and / or DisplayPort. HDMI you can also connect via adapter to monitors with DVI. Then each monitor gets its own cable to the PC.

What is often not possible to use the on-board monitor port in addition to a graphics card, because with many mainboards this is disabled, a graphics card is built into the computer.

If your graphics card has a Displayport port, this would be the ideal solution for you. You also need Displayport monitors, because here you can actually connect up to 4 monitors in a chain to the Displayport output of your graphics card, this is called Daisy-Chaining. Disadvantage: These most modern monitors rarely have an input for your PS2