Rainbow candies Level 307 Candy Crush

Younique_Natasha

I've searched and searched trying to prevent from asking this question but I finally got train tickets to move on to level 307 & I don't understand what the candies are with the rainbow flashes, that I think(?) seem to randomly change the candies? If you know what I'm talking about, would you mind explaining what they are & what they do? 1st time I've experienced them & am struggling w/the round bc I can't figure them out or find info. TIA! :-) 

Kar_Oz_Hi

Hey there. The flashing candies rotate between 2 colors; knowing that you can plan your next move.