The standard of hotels in Nepal is relatively the same as in the western countries. The only difference is that there is a problem of undrinkable water everywhere in the country, so it is not recommended to drink tap water or brush your teeth with it. However, you will be able to find drinking water jars where you can fill your water bottle.
If you use a travel agency to organize your trip to Nepal, then the hotels will be booked directly by the agency. However, you’ll have to pay for extras out of your own pocket.
Note: You’ll be able to pay with your Visa card in hotels in Nepal, but some of them only use cash, such as community homestays and some standard hotels. It is therefore very important to always have cash with you, as payments are generally made by cash.