to Triumphs and click on all the tabs that contain Account, Destinations, Events, Gambit, Crucible, Vanguard and Lore. Go into those tabs and press
to claim if available. Until you reach a total score of 5,000.
This is everything you've done in Destiny 2 so far.
This achievement can be glitchy and some solutions are; going to orbit, traveling to a different planet, and switching profiles to the profile select screen and just pick your profile again. The achievement should pop shortly after.
Apparently if you don't have the Forsaken DLC the Triumph points are capped at 3500**