"Breadcrumbs" is a line displayed usually at the top of your products catalog and showing where you're in the store.
Breadcrumbs are meant to show a visitor how deep within the navigation structure they are. For example, on a product page, you might see something like Store/Vegetables/Cucumbers:
If you believe that your customers do not need the breadcrumbs, you can hide them. To remove the breadcrumbs go to your Ecwid Control Panel → Design, the Sidebar section and uncheck Breadcrumbs: