This is the 242nd most frequent Polish word.
dziecko
Child.
Here, 'dziecko' is used as a singular noun to denote a young human being (child).
Dziecko bawi się w ogrodzie.
The child is playing in the garden.
Here, the root of 'dziecko' is used adjectivally in the word 'dziecinne', meaning 'childish', describing activities.
Czasu nie można spożytkować na dziecinne zabawy.
Time shouldn't be spent on childish games.
In this case, 'dziecko' appears in its plural form 'dzieci', referring to more than one child.