"JV the dispo" at 50/50. I nodded. What did I agree to?

A JV, short for joint venture, is a written agreement between two parties to work one deal together and split the fee from it. In dispo the common version is exactly what he described: he stays on the purchase contract with the seller, you bring the buyer, and at closing the assignment fee is paid to whichever entity the assignment agreement names. The JV agreement is what says how that money gets divided afterward. Putting both names on the seller-side contract is a different structure that some people also call a JV, and it changes who the seller can come after if the deal falls apart. So the term has a strict meaning and a loose market usage, and you should read the paper rather than the label.

50/50 of what is the thing to settle first. Some splits are on the gross assignment fee. Others net out marketing spend, title fees, and the earnest money deposit if it goes hard and gets forfeited. On an $18,000 fee with $5,000 of EMD in play, those two versions are a long way apart. Get it in one sentence in writing: gross or net, and who eats the deposit if the buyer walks.

The part that catches people newer to this is the buyer relationship afterward. If you bring your buyer to his deal, he now has that buyer's contact details, and nothing stops him from selling to them directly next time unless your agreement says otherwise.

One more thing since you're mid-licensing: whether getting paid to find a buyer for someone else's contract counts as brokerage depends on your state's statute and how it's structured, so ask a real estate attorney in your state before you take a fee.