Yes, when the region is active,
m marks all of the files selected by it. You can then act on the marked files.
But it can often be easier to use the mouse to select the files, and then use it to act on those selected. If you use Dired+ then you can do this. You can do more with the files, besides just marking them.
mouse-3 gives you a popup menu for acting on the files.
(If no region is active, then
mouse-3 shows a menu for acting on just the file where you clicked
If you also use library
mouse3.el (the code is here) then you can optionally use its popup menu, which is specially adapted for Dired, rather than the simpler menu shown above. Here is a screenshot.