R2T4 refers to a federal policy called Return to Title IV funds, a calculation used to determine whether or not you have “earned” all of your financial aid when you fail or do not complete your classes.
If you were to withdraw or be withdrawn from your classes before the end of the trimester or term, this calculation is performed to determine what percentage of the term you completed (number of days attended ÷ number of days scheduled) and how much of their federal financial aid they are allowed to keep.
If you completed less than 60% of your scheduled enrollment, you are not considered to have "earned" all of your financial aid. In this case, it is common that the school must return a portion of your aid to the Department of Education. In most cases, the aid for the term has already been applied to your tuition, books, or stipend, and can result in owing a significant balance to the University.
Please speak with your Student Advisor prior to dropping or withdrawing from a class. Having a conversation with your advisor, prior to withdrawal, can help you better understand if you will be subject to any repayment to the University.