The name or the word "Esen" actually means "well", "healthy", "peace(ful)". However, it also means wind that blows at a current time. In addition, it is a unisex name, although it has been mostly used for females after the 1980s, it was mainly used for males. [noted -ed]
I think Esen would be a pretty nice name. Not overused like Ashley, Sarah, Allison, etc. Esen makes me think of a German girl with brown and blond colored hair that's in long braids. Esen would also be a lovable character in a book. =)