Free play. 1 point is 1 penny. Minimum $5.00 redemption. You can redeem and activate it yourself at any slot machine.
Slot points are good for slot points play in the 365 days following the earning day. They can't be converted to any other use. The Wynn Rewards system has no provision to extend use/postpone expiration date. So, in the words of a Wynn Rewards boothling, "you might as well use them. They have no other use, and they're going to expire in a year." Because Wynn remains transparent in awarding slot points on a dollar-coin-in basis, slot points have an informational value. Unlike other programs, the Wynn win/loss will NOT tell you coin-in or coin-out. My final gaming activity each trip, therefore, is to screenshot my Wynn app to record Slot points, then play them off.
You can't convert them. But there's a separate bucket called Comp Dollars which is essentially resort credit. You can see that on the slot machines too. You can ask the front desk to help you apply Comp Dollars to your folio.
[slight aside] Even better to ask a casino host to do it. As I confirmed from experience in August 2022 (but had not experienced in April 2022), the front desk will leave the sales tax on the folio for the folio items for which you pay using comp dollars, with no way to apply comp dollars to the sales tax. However, a casino host using comp dollars to cover folio items will cover the items and then wipe the sales tax away. In either situation, comp dollars cannot be used to cover any tips on the folio. As always, be sure to fact-check me by referring to the Wynn Rewards terms and conditions document.