James is the only one named in scripture, but John 7 speaks of brothers plural.
Jude. He wrote the book of the same name.
James the younger is the son of Mary and Clopas. The second-century historian Hegesippus explains that Clopas was the brother of Joseph, the foster-father of Jesus. James would thus be Joseph’s nephew and a cousin of Jesus, who was Joseph’s putative son.
As for "brothers" plural, Jesus spoke Aramaic. Because neither Hebrew nor Aramaic had a special word meaning "cousin," speakers of those languages could use either the word for "brother" or a circumlocution, such as "the son of my uncle." But circumlocutions are clumsy, so the Jews often used "brother." The writers of the New Testament were brought up using the Aramaic equivalent of "brothers" to mean both cousins and sons of the same father—plus other relatives and even non-relatives. When they wrote in Greek, they did the same thing the translators of the Septuagint did.
In the Septuagint the Hebrew word that includes both brothers and cousins was translated as adelphos, which in Greek usually has the narrow meaning that the English "brother" has. Unlike Hebrew or Aramaic, Greek has a separate word for cousin, anepsios, but the translators of the Septuagint used adelphos, even for true cousins.