"Que Sera, Sera (Whatever Will Be, Will Be)", first published in 1956, is a popular song written by the Jay Livingston and Ray Evans songwriting team. The song was introduced in the Alfred Hitchcock film The Man Who Knew Too Much (1956), starring Doris Day and James Stewart in the lead roles. It was also featured in the films Please Don't Eat the Daisies, Heathers, The Glass Bottom Boat, Mary & Max, and Girl, Interrupted.
See more at Wikipedia.org...
Que sera is most likely to refer to "Que Sera, Sera (Whatever Will Be, Will Be)", a famous song
= lo que haya que de ser, será; lo que tenga que ser, será; que pase lo que tenga que pasar; lo que tenga que pasar, que pase. Ex: If you do this it should balance out some of the negative thoughts you're having and know that in the end que sera sera, what's meant to be will be .