This is the 3417th most frequent Chinese word.
弟
Younger brother.
弟" here maintains its general connection to a younger male, used metaphorically or symbolically.
这个故事的主人公是一名勇敢的小弟。
The protagonist of this story is a brave young fellow.
弟" is used as part of "弟弟", signifying 'younger brother'.
我的弟弟是一个很聪明的孩子。
My younger brother is a very smart child.
弟" is used colloquially as a suffix "小弟" to refer to a younger male sibling.