They rotate the weapon of the week ... you can dump all the tokens there if youre looking for masterworks cores (thats another source to get but not guarantee) or wait until the next dlc
I rather u go to the gunsmith, get a legendary engrams and the dismantle it for legendary shards. That's just me getting distracted by 999 materials :v
You turn them in for gear or consumables. Or use them when on the various planets. Or get them converted into items or armour or weapons. Each item will tell you what you should do with it.