When you start a business, there are generally expenses incurred prior to being "open for business". Things like purchasing equipment, buying advertising and the such. Those expenses incurred prior to being open for business are start-up expenses. For start up expenses it does not matter in what year they were incurred either. Some businesses can take several years to acquire all the business needs before that business can "open".
Start up expenses can be claimed in the first year the business is open and earning income. Even if the expenses incurred exceed the first year's income you still claim them all. Start up expenses get amortized and deducted over the first 15 years of business. If I recall correctly (and I'm not sure on this) you'll see those expenses listed as an amortized asset in the Business Assets section of the program.
