Non-verbal communications
“Kittens and cats that stare at others of their kind do so when they are feeling threatened, aggressive or hostile. But when cats blink at each other, they are giving each other a sign that they are coming in peace and that their intentions are friendly. A one-eyed blink is considered to be akin to a handshake or a hug.”
https://pets.thenest.com/mean-cat-squints-his-eyes-10198.html