

It means that the Game has no Memory of beeing run before so it starts the normal Installation Proccess and realizes it already has all Files. The Number 7 has to do with the Memory or Checklist i mentioned earlier. When you have installed 7zip you then Rightclick the File and should find an entry called 7zip in the Context menu.

Just do a quick goofle search and you should find a downloadlink for the software. To unpack the data you nee md the free software 7zip. i put an "x" before Honkai to better recognize it later. Even though it should not break anything i would recommend just renaming the Registry Folder so that you can reverse any changes that might make it worse afterwards. By delete Honkai impact 3 he means the Registry Key (you are essentially editing the Memory list of the System so that it forgets what it has done in the past).
