子供(こども)のころ、よく公園(こうえん)で遊(あそ)びました。

This sentence talks about a past childhood memory, specifically the frequent activity of playing in a park during one's youth. It's a nostalgic way to share personal experiences from the past and what you used to do.

子供の時の思い出、公園でよく遊んだことを伝える表現です。