The payment amortizes the balance at the rate and term you enter, compounded monthly. Interest over the term is the sum of the payments minus the starting balance. Extra payments, when the form has that field, shorten the term the same way an extra mortgage payment does.
A $30,000 balance at 6% for 10 years has 120 payments. The payment is higher than $30,000 divided by 120 because of interest. A longer term lowers the payment and raises the interest.
This is not a Canada Student Loan or Repayment Assistance Plan calculator. Income-driven payments, subsidies, and forgiveness are not applied. The rate stays fixed at the rate you type.