This is an old Russian toy called Nevaliashka (Неваляшка) or Roly-poly in English. These toys were normally meant for younger children since they were considered safe to play with and also reasonably hard to break.
These toys were extremely popular during Communism, not only in the Soviet Union but also in all of the satellite Eastern block states.
The toy is hollow on the inside with the exception of a heavy center that is positioned at the bottom of the doll which prevents it from falling over.
Condition as seen in pictures.