A mortgage payment is the money you pay back the lender, often made once every month.
There are other payment terms though, such as bi-weekly mortgage payments. In any case, if you have a fixed-rate mortgage (FRM), then payment would remain the same throughout the life of your loan.
As for what goes into a mortgage payment, there are three basic elements:
Principal
This refers to the amount of money you'll borrow.
Example
Say the home you want to buy is worth $200,000, and you already saved up $20,000.
You can use the latter to make a down payment so that you only have to borrow $180,000.
The $180,000 is the principal loan amount. That's what the lender will place the interest on.
Interest
Since we're talking huge amounts of money here, it makes complete sense lenders want "compensation" for the risk they're about to take. They aren't 100% sure they can get their money back, so they place an "interest rate" on the principal.
Interest is the amount of money you pay after the lender applies the mortgage interest rate. Make sure you don't confuse mortgage rates with APRs (annual percentage rates).
Example
Most mortgage rates are only one digit with decimals. An example is the most recent average rate of around 4.50% for 30-year FRMs.
Say you'll borrow $200,000 with a mortgage rate of 4.50% and a term of 15 years. You can then expect to pay around $1,529.99 your first month.
Additional Considerations
Depending on the home you buy, you may also need to pay homeowner's association dues, hazard insurance, taxes and similar fees.
Term
This is the length of time given to you to pay off your entire mortgage.
Example
If you take out a 15-year mortgage, you have a term of 15 years. That means you have 15 years to pay back what you owe the lender. That gives you less time, but that also means you can be debt-free sooner.
If you choose a 30-year mortgage, the lender will spread your mortgage schedule payments over 30 years. That means lower payments every month, but it also means being in debt longer.
Also, the longer the term, the more expensive the loan, since a lot of your money goes only towards interest.
Additional Considerations
Which type of mortgage is best for you depends on your unique situation. It's for this reason you should always explore all your options.
Start by comparing mortgage offers from different mortgage lenders.