The page uses two phrases for the same promise.
The two wordings
The body text says 60-day satisfaction guarantee. The metadata and badge image say 60-day money-back. The page also says terms are set by the seller.
What to do
Treat satisfaction guarantee as the safer reading and check the actual terms at checkout. The page also says the clock runs from the purchase date in one place and suggests counting from when your order arrives in another. Assume the earlier date and act early.
Educational note: This guide is general information based on the Quiet Nerves page. Statements have not been evaluated by the Food and Drug Administration. The product is not intended to diagnose, treat, cure or prevent any disease. Individual results vary.