When the update drops, you'll get an opportunity to procure Blueprints from each online Rocket League coordinate you Rocket League Items play. Whenever you have a Blueprint, there are three things you can do with it: construct the thing in the Blueprint (this requires Credits), exchange it to another player, or keep it with you. All Crates you have in your stock will be changed over to concealed Blueprints after the update. Just Blueprints that used to be Crates will be concealed, however you can uncover what thing the Blueprint will work at no expense. After it's been uncovered, you'll have to spend Credits as regular to construct the thing in the Blueprint.
There are likewise some new principles around player-to-player exchanging. You'll have the option to exchange any uncovered Blueprint to different players, just as the things they manufacture. Also, you can exchange free drops and tradable things you procured before the Blueprint framework was presented. You won't have the option to exchange concealed Blueprints, so uncover them before you exchange them.
On the official Steam declaration page, Psyonix gives a helpful guide regarding what's tradeable and what isn't. Here's Buy Rocket League Items that manage in full.