@ag - add missing libspec is code action that the server can execute on this position. Apparently, it shows it always, no matter whether the action can be executed or not.

About the color of the background - I think it comes from markdown-mode.

You could try to click on it and then do M-x describe-face

Hello ALL, is there any way to open more than one instance of Emacs?

Do you mean multiple windows (also called frames in Emacs terminology) for the same Emacs process? C-x 5 f or C-x 5 b with default key bindings can do that.

If you mean a completely separate process, typically invoking 'emacs` from a terminal window on Mac and Linux machines will start a separate emacs process, unless that command has somehow been aliased with additional options, or made an alias for a similar command called 'emacsclient' that creates a new window for an existing emacs process.

Comparing the buffer lists produced from typing C-x C-b between two windows can help confirm whether they are the same or different emacs processes (same buffer list always if same process, but can differ if different processes)

to add to these good tips, i do C-x 5 2 to get another frame. i also use multiple emacs instances and use the buffer list technique described. although it can be convenient and more robust sometimes, consistency / up-to-dateness of information in things such as recently used files and such can suffer.