Sections are the primary containers and they are used to create groups of columns. Sections can have different layouts, paddings, margins and layout settings. For details about section settings please refer to this article
Sections can have boxed and full width content width, which can be selected in layout tab > Layout section in Elementor’s section settings
Boxed content width places the content inside sections within the page body container.
Full width content width overrides the body container width limitation and puts content on the full available width.
Sections can have default height or be full height. Moreover, you can manually specify the height of the section. To choose between this options, go to Layout tab > Layout section in Elementor’s section settings and use “Height” selectbox