This is the 3416th most frequent Japanese word.
深
"深" means "deep" or "profound" in English.
Here, 深 is used as an adjective '深い' to describe the depth of the lake.
この湖はとても深いです。
This lake is very deep.
In this sentence, 深 is a noun form '深さ,' indicating the profoundness or complexity of thoughts.
彼の思想には深さがあります。
There is depth to his thoughts.
This example uses 深 as part of the adverb '深く' to describe the manner of thinking, emphasizing its seriousness.