Usually this happens because your gas is too low. If it’s still pending many hours later you may have to submit another transaction with the same Nonce (transaction number- found in the advance tab) and offer more gas for the transaction. Only then will the second higher gas offer replace the first lower gas contract.
Looks like the transaction is now successful is confirmed: Ethereum Transaction Hash (Txhash) Details | Etherscan
For future transactions, please check: Pending "Stuck" Transactions