In Laravel, @yield is principally used to define a section in a layout and is constantly used to get content from a child page unto a master page.
So, when the Laravel performs blade file, it first verifies if you have extended a master layout, if you have extended one, then it moves to the master layout and commences getting the @sections.
@yield, it always gets the section from the child layout. That means it always overrides the @yield part, even if it has a default defined as @yield
Hope it helps!!