This is the 4188th most frequent Japanese word.
不断
"不断" means "continuous" or "constant."
In this sentence, '不断' is used as an adjective to describe the persistent and ongoing nature of the subject's effort.
彼の努力は不断です。
His effort is continuous.
Here, '不断' modifies '学び', emphasizing that learning should be unceasing and ongoing.
不断の学びが重要です。
Continuous learning is important.
The word '不断に' is used as an adverb, indicating the continuous and consistent action of self-improvement by the subject.