@hellomiakoda It's a custom in Zoroastrianism and Tibetan Buddhism where a corpse is put on top of a platform to be eaten by vultures.
In Tibetan it's called "bird-scattering", but for some reason "sky burial" is the standard term in English.
For Buddhists, it's one last act of generosity. The Zoroastrian motivation is to avoid defiling clean Earth with decay, but nowadays they also emphasise it as a final act of charity.