A business or organization is nonprofit if its main purpose isn't making money for its owners. Nonprofit companies usually raise money for charities.
You can use the word nonprofit as an adjective or a noun — a nonprofit is an organization that benefits some public good, rather than raising revenue for stockholders or owners. There are educational nonprofits, religious nonprofits, public health nonprofits, and many others. The word's been around since the 1920s, combining non, or "not," with profit, from the Latin root profectus, "advance, increase, success, or progress."