New objects "attached" to each other just started using bleder two weeks ago, I did a few tutorials and it went OK.

today I started a new one, but when I tried to add a primitive it kind of related to my first object. it doesn't have an independent name (all of them named 'plan' in the panel) and I can't select\edit only one of them. How can I fix this?
Add them in Object Mode not in Edit Mode. You can also select the vertices of one of the objects in Edit Mode and press P, to make a new object from the selection.