A mortgage is simply a loan that is secured on immovable property, normally your home, hence 'home loan'. The mortgage is lent to you in a lump sum to pay for the property and is legally bound to the property by the attorneys who register your mortgage bond. You then have to pay back this mortgage over a given length of time.
This time period is usually 20 years, but it can vary between 5 and 30 years depending on circumstances.
'Secured' means that if you don't make payments as you agreed, the lender has the right to sell your property in order to recover their money. This is rare but it is important to understand from the outset that if you do not keep up repayments on your mortgage you are at risk of losing your home.