Hello @Moira
Thank you for your response! I’m completely new to this and still don’t understand a lot of things in this sector. But thank to you I’m reassured by your explanation that not all pages need to be indexed. Here I am glad that it is not as critical as I thought 
Even so, I would say that I have a lot of pages that are not and should have been indexed and here I would like to ask you for a little more explanation.
I understand that there are some errors that need to be fixed, but it is not clear to me how exactly to fix them.
I am sending you screenshots of these problems. I’m sorry, but I can’t change the language settings from czech language to english, but I hope you can understand
The biggest problem seems to be with “canonical pages”. I have tried many times to delve into the problem, but even after spending a day, I simply do not understand what I should do and where 
Would you please be so kind as to advise me on what steps I should take? Thank you very much in advance.
Eliska