What Does Set to 256 Mean?

So, I'm 11 years old. And To Be Honest I'm A Computer Geek. So It Was Kinda Embarrassing When I Was On The Minecraft Server I Co-Own, And We're Working On Skywars Maps, Well I Don't Know Much About Skywars, so when I get on, Michael (The Main Owner) Asks Me To Go To Another Corner of the map and "Set It to 265" well. I Have No Clue What That Means. So If Someone Could Please tell me (geeks, you can come in handy) What that means and what's the command to do it, Thanks (Please make it simple, I'm not the Sharpest Knife in the drawer when it comes to skywars)

Guest

To switch your display to 256 colors
Some games and other software programs require that your monitor be set to 256 colors, or they run better in 256 colors. Many of those programs will switch your monitor to 256 colors automatically when you start the program. For those that don't, follow the steps below if you want to switch the display temporarily while the game or program is running.
1.
On your desktop or on the Start menu, right-click the game or other program that you want to run in 256 colors, and then click Properties.
2.
Click the Compatibility tab.
3.
Select the Run in 256 colors check box.
Note
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The screen will revert to your default color quality when you close the program.
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Try switching to 256 colors if your software program shows the wrong color or the graphics redraw slowly.
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If your software program appears in a small window in the center of your screen, you can increase its size by changing your screen resolution temporarily. Follow the procedure above, but in step 3 select the Run in 640x480 screen resolution check box. Your screen resolution will revert to its previous resolution when you close the program.
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The Compatibility tab is available only for programs or games located on your computer's hard disk. It is not available if the program is stored on a floppy disk, compact disk, or a network.

Ron