No posts or no pages are published, and you haven't set them as [Homepage] on Reading Settings.
Publish one or more posts or static pages
Set the published page or the latest posts as Homepage.
Make sure one or more posts or pages are published.
Make sure "Your homepage displays" are selected as "Your latest posts". Or "A static page" is selected then both of [Homepage] and [Posts page] are chosen different page.
"Your latest posts" is selected
"A static page" is selected.