What does it mean "liberation from samsara"?

In short, it is the cycle of death and rebirth. Saṃsāra is sometimes referred to with terms or phrases such as transmigration, karmic cycle, reincarnation, and "cycle of aimless drifting, wandering or mundane existence" ... The liberation from Saṃsāra is called Moksha, Nirvana, Mukti or Kaivalya.

Explanation:

this is it