You can manage the content of your website's homepage from admin panel, go to 'Pages', and click 'Home' page link. Depending on which template you are using, the required content area for its homepage will also be different. Some will have both carousel and highlight menu, some will have latest display of menu you appoint, etc.
Carousel is big pictures slideshow you can upload images onto. You can switch 'On' and 'Off' for images you want or not want to display.
Highlight is a snippet which can be used to display some overview information about your website and images. For example: if you want to let your visitors know about your company or organization, then you can customize the highlight section to show a snippet of your 'About Us' and linked it to the 'About Us' page.