It is a type of mortgage that uses a fixed interest rate during the whole term of the loan.
Unlike adjustable-rate mortgages, with fixed-rate mortgages, the client and the bank agree on an interest rate that will not change for the entire duration of the mortgage.
Fixed-rate mortgages have a higher starting rate than adjustable-rate mortgages and shorter repayment periods. In exchange, they are safer because you know at all times what you will pay for the loan.