A washer and dryer rental is exactly what is sounds like: Companies offer you the ability to rent a washer and dryer for your apartment.
There are a number of companies that offer this service for people who might not want to spend thousands of dollars by purchasing a washer or dryer for a rental unit.
There are a number of things to consider. Some apartment buildings are so spread out that it might be worth it to rent an in-unit washer and dryer so that you don't have to lug your clothes back and forth long distances. And, some complexes don't offer washers and dryers at all, so doing laundry is a huge chore that must take place at a laundromat.
Having your own washer and dryer will save you an exorbitant amount of time. Don't forget to consider the cost of this service. Some companies might offer reasonable pricing, so it's worth it to check out.
Use Google to search for washer and dryer rental services in your area. You can compare pricing and decide if it's worth it for you.