In the main*, you can only have one track selected, because this is what diverts incoming MIDI to the relevant environment object.
Why do you want to select multiple tracks? If it's to select the regions on multiple tracks, then holding shift while selecting tracks will add that track's regions into the selection.
If you want to do something like drag 10 tracks down the track list at once, you can't do that in Logic, you have to move them individually, which is a bit of a pain.
* There are a few exceptions, but for brevity I'll avoid them for now.