What exactly is a business plan and why is one created?
Business plans are created to accurately plan the business and maximize its chances of success (own goals), as well as to convince third parties, such as the company's board of directors, a private investor or a bank, of the project. It is a detailed plan for the development of your business.
Normally it consists of a descriptive section and a financial section. A simplified business plan can be 10 pages or even one (business model canvas), but there are also documents of several hundred pages.
It all depends on your needs. Interestingly, business plans have a similar form all over the world, so they can also be used abroad after translation.