I have heard these mentioned a few times from higher level discussions. What are bright engrams?
You must be level 20 before you can do anything with these and chances are you wont start getting a lot of them until you reach level 20. You wont be able to bring these to regular cryptarchs, instead you need to bring a bright engram to Tess Everis who is the rep for the Eververse Trading Company and she will be able to unlock the contents inside.
Bright engrams contain special items such as weapon mods, skins, armor pieces, exotic sparrows, bright dust and some other uncommon items. You will get a bright engram every time you level up after level 20, so you will end up getting a lot of these over time.