This one is easy - It's Old English (or Anglo-Saxon), leof meaning "dear, agreeable, beloved" (as seen in Leofwine and Leofric) and stan meaning "stone" (as seen in Athelstan and Dunstan).
You could have found that out yourself quite easily, by doing searches for "leof*" and "*stan" on the main page (www.behindthename.com). I don't mind helping you out with these queries, but it would be better if you learned to research the easy ones yourself, and only posted the ones that aren't so easy.
♦ Chrisell ♦
All we have to decide is what to do with the time that is given us. - J.R.R. Tolkien.