A YouTube embed code is an HTML snippet (usually an iframe) that allows you to display a YouTube video directly on your website or blog without visitors having to leave your page.
YouTube no longer allows completely hiding related videos. However, by turning off the "Suggest Videos From Other Channels" toggle, the player will only suggest other videos from the same channel when the video finishes.
The "Make Responsive" option wraps your iframe in a special CSS container so that the video automatically resizes to fit any screen size (like mobile phones) while maintaining its correct aspect ratio.