Scotch bonnet peppers are very spicy chili peppers that are native to the Caribbean. They're similar to Habaneros, which are more common here in the US, so I use them interchangeably. Scotch Bonnets are very spicy - far spicier than your average jalapeño. However, they also have an incredible fruity flavor that can be imparted into dishes without overwhelming them with spice. In this recipe, the whole pepper is added to the pot with the rice and beans as they cook to infuse it with flavor. If you just leave the pepper whole, it really won't add much spice at all. I like to make a small incision on one side of the pepper so that it can release more of its flavor and a little bit of its spice into the dish. You can also split the pepper in half if you want lots of heat. If you are very opposed to heat and cannot tolerate any, or if you simply cannot find Scotch Bonnet or Habanero chilies, you can leave them out altogether. You can also look for a chili called "Aji Dulce," which has a similar fruity flavor to a Scotch Bonnet without the intense heat. Aji Dulce are not commonly found in grocery stores, but you can often find them at Latin markets.