It's a song from the movie The Myth as seen on the title. hehe and yes, it's sung by jackie chan and korean actress kim hee sun. The lyrics are really nice and the tune is great, soulful and melodic. There's even piano versions and one in particular is really nice.
I haven't watched the movie but if you click on the title, it leads you to the song and movie trailer. Although the movie might not be to everyone's taste, you might want to listen to the song. It's soothing.