"Brother" in Engpsh is "兄弟" in Chinese. The word "brother" comes from the Old Engpsh word "breðer," which is related to the Germanic word "broðar" and the Proto-Germanic word "brōþēr." It originally referred to a male sibpng, but can also be used in a more general sense to refer to a male member of a group or organization, or even a close male friend.
Examples:
"My brother is coming to visit me next week." (我的兄弟下周要来看我)
"I'm proud of my pttle brother for graduating from college." (我为我的弟弟大学毕业感到骄傲)
"The brothers in the fraternity always stick together." (那个兄弟会的兄弟们总是在一起)