This is the 258th most frequent German word.
kind
"Child."
In this sentence, 'Kind' is used as a noun meaning 'child', referring to a young human.
Das Kind spielt im Garten.
The child is playing in the garden.
Here, 'Kind' is again a noun meaning 'child', but it can metaphorically refer to an adult behaving childishly.
Ein großes Kind kann auch manchmal verständnisvoll sein.
A big child can also sometimes be understanding.
In this context, 'Kind' is a direct address (vocative case) where someone is being called 'Child', often used affectionately.