Slow your roll means to "slow your role." or chill the fuck out.
A commonly misunderstood slang term due to that fact that it is often mispelled. Although a valid interpretation is possible with the incorrect spelling intact, the phrase makes little sense to individuals who are less knowledgeable.
Black Guy: Yeah 'B', i had to tell them niggas at work to slow they rolls na'mean
White guy: Yeah! But why would they want to lessen the amount of money they make?
Black Guy: Na bruh' I mean CHILL the fuck out.
White guy: But how are they susposed to get diamonds if they are making less money?................