Can anyone explain how to use the "CTRL" button

I'm a newbie and just found the studio online and started using it but while doing the tutorials it told me that I could use "ctrl"to get to the color picker how do I do that?

Hold down Left Alt key for the color picker.

For that, you have to select specific content in your code and press CTRL. If you do it while your keyboard cursor is on a number for example, you can select a number in a specific range.

To open the color picker, you need your cursor to be either in a hex color ('#fad' or 'rgb(41,42,213)' for example), then you press CTRL to open the color picker.