Hi. You see, I created a region with notes and an empty region appeared, too. I don't remember, did it appear itself or I created it. If itself, then why? Why is it as clued to the other? The problem is, I wanted delete the empty one but with that was deleted also with notes. Then I noticed, they are also moving together. Why they are together and how can I separate them? I grabbed to left back and after some attempts they separated. But as much as I understand, I grabbed them the same way resulting together or separated. For what is it good "clued" regions? Video is included. https://youtu.be/y4bWlcXfy58

You probably created the extra region by Command-clicking in the background -- a Command-click temporarily turns the cursor into a Pencil tool (for adding Regions). The Regions are moving together because they're both selected (highlighted) -- click somewhere in the background to de-select both, and then you should be able to select them independently and move or delete either one.

Is there anymore difference between highlighted moving together regions and normal separated regions than their look? What is an idea of "clued" regions?

A highlighted Region means the Region is selected -- if multiple Regions are selected [highlighted] and you move one they'll all move. GB has no "clued" [I assume you meant "glued"] Region feature, other than selecting several Regions at once. [Logic has Mix/Edit Groups, but AFAIK that feature is not included in GB]

I tried to create an extra region, tapping on cmd click, nothing happened. Why? Video is included. https://youtu.be/4d4E9hyffHg

In the end of this video, I tapped on the timeline and what I call ruler (a wide colour line in piano roll) turned from light green to dark green. What it means?

1. Holding Command should turn the cursor into a Pencil -- then clicking in a track lane should create a new empty Region 2. In GB the Ruler is the timeline above the the track lanes with the bar/beat numbers in it. I assume you're talking about the title bar of a selected Region, which would be light green -- if you have a Region selected and you click elsewhere in the tracks area you'll de-select the selected Region. I've attached a link to a basic GarageBand course [above] that should clarify some of these things..