what are prizeboxes on here?

[X Skilled X]

what exactly are the prizeboxes that are being offered as a reward in the sythe easter event?

 

They're miniranks that function as loot boxes pretty much. The higher tiers give you a better reward when you open them or you can just leave them on display.

You can also resell them for money in the sandbox. Higher tiers go for way more than tier 1. Tier 1s are spawned very often since donations are rewarded. Explained better here: Sythe Prizeboxes