Facebook gives you ability to like other pages “as your Facebook page” and these pages show as your favorite pages on the right side of your page. Its a very easy and nice way to advertise / promote another page.
To like a page “as your page”, go to that page and click at the gear icon located on the right side of the page, under the cover photo. From the drop down option menu, click at “Like as Your Page…”.
A new modal window will open with the list of all your pages. Select your page and click Save button.
Go to you page and you will see newly liked page in “Likes” section of the your page.
If you want to remove a page from this section, go to that page, click at the gear icon and select “Remove from My Page’s Favorites”.