Footer provides additional navigation at the bottom of your website.
FOSE is primary component name for footer sections, where FO - footers, SE - sections and last 2 digits is a sequence number.
Section components shouldn't be nested inside of sections, as they already built upon it. You can select and copy any section component from the styleguide and paste to your project or you can search the component's name in the Component panel (Shift + A) or use quick search (Ctrl + E).
Before making any changes you need to unlink component. Right-click on the symbol’s label and choose unlink from symbol. You can style components whatever you like.