Since this is in the Real Estate section, I am sure you mean rent-to-own a house. It means that you will pay a monthly lease amount. Sometimes a portion of the payment will be set aside to go towards the purchase price or down payment (it would be lost if you didn't end up buying the home). Usually there is also an "option fee" around 5% or at least a couple thousand dollars that would also go toward the purchase price when the home is bought. After a time, usually 1 or 2 years of leasing, you would make arrangements to get a mortgage.
These types of arrangements can be beneficial to the person that will be buying the home because they usually lock in the current price of the home, even if the other homes in the area appreciate in value. They also give the buyer time to rebuild their credit or sell a home in another state. The buyer would be wise to make sure it is a home they really want before entering into one of these contracts, have an attorney look over the contract and talk to a mortgage lender to see what kind of time frame they would be looking at to be able to obtain financing.
These can be beneficial to the seller because they sell the home in the end (if all goes well). If the home isn't purchased, they at least get to keep the "option fee" and any other rents that would have gone toward the purchase. Plus, in either case, they have someone that is more than just a standard renter. The person living there may be more inclined to take care of the place because they think they will own it in the end (which should be the goal for all involved).
There are some scammers out there, so beware. Some are just in it for the profit and really don't care if you end up owning the home in the end or not. In my opinion, it would be better to ask people that are already trying to sell their home to see if you could work out a deal.