but for the common use case (like mine) where someone creates social network and has group with very popular theme (cannabis,) in this case-   nobody can see him and the work is for me now.   this is foolish because software can fix him, so i can have time for more things of some other kind.
please advise, thank you :) does this help to understand me now?

no, i want everyone to be able to see the group and attempt to join it, but only what the name is, the groups photo, its decription, but none of the content, until they are a member.   this to me is "secret group"
closed group is correctly in english " group you can see and read but cannot participate or add to"
and open group is group anyone can join and add to without need to moderate admission/membership.
this is something facebook gets wrong, and you guys have also gotten wrong.
my suggestion is just go with what makes sense in english, ^^ the above, and make a lot ofpeople happy in the future.  

:) hope that makes more sense