Lesia Valadzenkava or Volodenkova (born 1 May 1991) is a Belarusian ice dancer. With partner Vitali Vakunov, she is a two-time Belarusian national champion.
I know a Ukrainian woman named this, who pronounces it LESH-ah. However, she also goes by Alex (I guess as an Americanized nickname), so I'm guessing Lesia in that case is short for Aleksandra.
Lesia is also a Ukrainian name. I met a woman named Lesia and she pronounced it LAH-sha. There's also a book about a Ukrainian girl called "Lesia's Dream."