The maximum credit line is 5,000 yuan, and the outstanding amount is 400 yuan. The credit line is 5,000 yuan, which means that the maximum credit line of revolving loan obtained on the online lending platform is 5,000 yuan, which means that the outstanding amount of revolving loan is 400 yuan. In other words, 400 yuan has been loaned from the credit line, but it has not been fully paid off.