What is apple turnover?

A type of Danish pastry/

Great to eat, not sure you can use it as a program!

"Turnovers" are usually triangular shape puff pastry dough, filled with fruit, folded over and sealed by pinching the dough, and then baked.
Like a big fruit samosa, if you are from that part of the world.

OOPS! You asked this under computers.

This may help.

Learning from Apple's HR Strategy for Turnover Rate KPI