Amortization describes how a loan is paid down over time. Each fixed instalment is split between interest (calculated on the outstanding balance) and principal (the original amount borrowed). Early payments are mostly interest; later payments are mostly principal.
Swiss mortgages are unusual — they are often only partially amortized. Owners must pay down to 65% loan-to-value within 15 years, then the remaining mortgage can roll indefinitely. German, French and Italian mortgages are almost always fully amortized to zero.
An amortization schedule lists every payment, splitting it between interest and principal and showing the remaining balance. It is the clearest way to see how a loan actually unwinds and how much interest you will pay over the life of the loan.
On a EUR 200,000 loan at 3% over 20 years, the first monthly payment of EUR 1,109 contains EUR 500 of interest and EUR 609 of principal. By the final year, almost all of each payment is principal.