What it means
The swap carried a deadline and did not get mined before it passed. Deadlines protect you from a transaction sitting in the mempool for an hour and executing at a stale price. A too-low fee is the usual reason it missed the window.
How to fix it
Retry with a fresh quote and a market-rate fee so it mines inside the deadline. If the network is congested, a longer deadline in the dapp settings also works, at the cost of more price movement risk.