noun
Que Sera, Sera (song title); Whatever Will Be, Will Be
Refers to the song 'Que Sera, Sera (Whatever Will Be, Will Be)', popularized by Doris Day. In Japanese, it is used as a borrowed phrase meaning 'what will be, will be' or to express a carefree, accepting attitude.
母はよく「ケセラセラ」と言って、あまり心配しない。
My mother often says 'Que Sera, Sera' and doesn't worry too much.
ケセラセラの精神で、なるようになるさ。
With a 'Que Sera, Sera' attitude, whatever happens, happens.