How it's worked out: using your device's local time and the Eastern time zone (America/New_York, including daylight saving), it checks whether the US regular session is open right now (Monday to Friday, 09:30–16:00 Eastern). US public holidays and pre/after-market hours are not counted, so the market is actually closed on holidays and there are separate pre/after-market sessions. This is a reference only; go by the exchange and platform announcements. On-chain tokens transfer 24/7, but their fill prices and liquidity still track US market hours.
Why the hours matter
Outside trading hours the on-chain order book is thinner and more likely to drift off peg — see trading US stocks around the clock and fees and slippage; to estimate slippage, use the slippage estimator.
Open a Binance account and wallet, then wait for a session with better liquidity before trying a small amount — it's steadier.