Post Navigation Area is an area under the main menu. This area is created using a single page and will be displayed only if you choose Static Navigation with post-nav Area as Navigation Layout Type.
To Set up post navigation area, follow the steps below :
Step 1 – Navigate to Page > Add New then design a page.
Step 2 – Navigate to Appearance > Theme Options > Main Navigation.
Step 3 – Choose Static Navigation with post-nav Area as Layout Type.
Step 4 – Turn ON Show Post Menu Page.
Step 5 – Choose a page to use as Post Navigation Area by selecting Select Post Menu dropdown.