Executing a transaction on the Ethereum blockchain requires a fee to be paid called the "gas fee".
When this fee is set to a low amount it can cause transactions to be delayed.
The Ethereum network is witnessing very high gas fees for transactions. Please adjust the gas price to reflect your current needs regarding cost and time. You may want to reference a third party source such as https://ethgasstation.info/ or https://etherscan.io/gastracker for a recommendation on what gas price to select.
Please find more information here on how to adjust Gas Price and Gas Limit in Metamask.