[nohaydeprobleme]

In most cases for „der Bruder“, the answer is yes: the plural is „die Brüder“.

But in the dative (Dativ) case where the "brothers" are an indirect object, the plural form has a different spelling. The singular „den Bruder“ transforms into „den Brüdern“. For example, if you want to say "I gave it to the brothers," you can say: „Ich habe es den Brüdern gegeben“.

To figure out the plural forms, I use the online Leo dictionary (e.g. at https://dict.leo.org/german-english/bruder), which often includes a table icon for indicating when the noun endings change in other cases.

For studying plural forms of any noun, you can follow general rules for pluralization and individually memorize the plural forms of each noun with flashcards. You can also read and listen to native content to develop an intuition for what sounds right.