You probably mean delta, which just means major as far as I know. You'll also sometimes see this symbol next to a minor chord, which means a minor chord with a major 7.
It has a bunch of chords that having nothing. Which I'd assume are majors's. I know whatr 7's are. And Now I know that the -'s are minor. but this delta really gets me. Its not infront of a minor chord. But it is infront of a Bb chord and almost all the rest of the Bb chords are 7's so do you think its just giving me a little extra reminder that its not a 7 this time its a major?