Their group was called “the Brotherhood”.是什么意思？

Their group was called “the Brotherhood”.

他们这群人称为“兄弟会”。

their

pron. 他（她，它）们的，在提及性别不详的人时，用以代替 him 或 her；

例句
Their permissiveness toward their children reflects the wild abandon of their own lives.
他们对孩子的放任折射出他们自身生活的放浪形骸。

group

n. 组，团体，群，批，（雕塑等的）群像，（英美的）空军大队；vt.& vi. 使成群，集合；vt. 分类，归类；

例句
...a group of youths riding their motorbikes four abreast.
驾着摩托车，四个一排齐头并进的一群年轻人

was

v. 用来表示某人或某物即主语本身，用来表示某人或某物属于某一群体或有某种性质（ be的过去式 ），在，存在，不受干扰；

例句
There was a terrible sadness in her eyes...
她眼神中流露出深深的悲伤。

called

v. 叫( call的过去式和过去分词 )，通电话，认为，估计；

例句
He has also called for an acceleration of political reforms.
他同时呼吁加快政治改革的步伐。