A form of
salutation or greeting.
Its first form is the word bro, being used multiple times in a row. This usually happens when the person repeatedly saying "bro" is excited, trying to get someone's attention, or high.
Later on, this was adapted.
The bro is said only twice, and not repeatedly however times wanted, and a new word follows -
bruda. This word comes from the german word for brother,
Bruder.
The phrase "Bro bro bruda" is now used for the same reasons as repeated bro is, and it is newly also used as a greeting to someone you haven't seen in a long time.