This is a classic baby rattle/teething toy, often known as “Baby Teething Rattler”.
This toy is primarily designed as a safe teething ring for infants and toddlers during the teething phase to relieve gum itchiness. When shaken, the plastic discs clatter gently against each other, creating a rattle sound to capture the baby’s attention.
These toys were very popular in the 1950s and 1960s. They were typically produced by vintage toy companies such as Plakie Toys.
