A weird way of saying, "brother from another mother".
Only people who are not actually related to you are referred to this way.
It can also only be used as a direct statement to someone, you can't refer to people like "he's my brolander" or anything like that, and if you do, you're a savage.
Tom Hanks: Yo, will smith, what's up Brolander
Will Smith: Not much just buying more slaves.
Tom Hanks: no way me too!!!