Psalm 133:1 KJV
Behold, how good and how pleasant it is for brethren to dwell together in unity!
Psalm 133:1 GW
See how good and pleasant it is when brothers and sisters live together in harmony!
Are we just talking about males?
In Hebrew and other Semitic languages, it is standard for a group of males and females (even if there is only one male and the rest females) to be referred to by a masculine-gendered noun or pronoun. The Hebrew word is אַחִים (achim) in Psalms 133:1, meaning "brothers," but this is not necessarily to the exclusion of females, due to the rule mentioned above.