Here is where you'll add an overview of your business. You have basic word processor controls for adding styling like bold, italic, and bullet list items. The length here is up to you, but it's better to limit details to just the basics. Two or three paragraphs are plenty; booth visitors will interact more with things like video and photos, rather than reading a lot of text.
In this section, you can also set a highlight color for your booth. This will change the color of things like icons and buttons. You won't be able to add a custom color, but you can choose from a pre-set selection that complements your brand.