Gentleness is defined in many places and ways, but basically, it is being intentionally kind, compassionate, and humble towards others, especially when they are facing struggle or difficulty.
[Jesus said:] “Come to me, all you who labor and are burdened, and I will give you rest. Take my yoke upon you and learn from me, for I am meek and humble of heart; and you will find rest for yourselves. For my yoke is easy, and my burden light” (Matthew 11:28-30).
Obtained from https://www.ccvichapel.org/post/gentleness-gentileza