This is the 218th most frequent Japanese word.
子供
"Child" or "children."
Here, "子供" refers to a young child as a subject of the sentence.
公園で子供が遊んでいます。
The child is playing in the park.
In this context, "子供" is used to generally describe children as a group.
子供の成長は速いですね。
Children grow up quickly, don't they?
In this sentence, "子供" is used to indicate children in the context of their right to safety.