Yes. Or out of focus. If you have one monitor, three virtual desktops would be like having three monitors. Looking at a different one, doesn’t stop anything running on another. You can also “send” a window on one desktop to another, equivalent to dragging a window from one monitor to another when using two or more.
KDE Activities is a similar feature, but it can actually suspend everything running in a certain “activity” when you switch to another, if that’s something you want.