First thing is on top always. Yes? We say yes also. Turning on or off multi languages will cause a large change to your website. Redirection on pages will be different so be aware of this. It is not an warning just friendly word from admin.
So first step is to add language, then setup flag or icon to be recognisable for you and users because it will be displayd in language choice bar.
Then you can translate your language file which name is listed in language bar on this admin page. So play a little bit with this language issue, but be carefull when you playing with a live site links are going to be different.
Image above explanation:
1. Edit flag
(delete and upload new icon for language)
2. Set language active and visible
on web pages (yes) or not (no)
3. Linked file
for language (edit thrue file explorer)
4. Title and description
of INDEX or first page on web site
5. Delete lang
completely (will remove and DB tabels also)