First of all you need to know that there is a difference between liking someone's page (this could also be a business), and placing 'like' at the end of a post. "Like" means that you.... well... like something, or appreciate what was posted or shared.
Liking a page is like putting your endorsement to a page - usually a page about a certain subject or a business. Once you like a page, you will receive posts that the manager of the page (the owner) shares with you. Have a look at these two images:
Just for practice, you could try liking my Leah's Kitchen Page, which is a page dedicated to everything about food and in particular about gluten-free food: https://www.facebook.com/Lsabankitchen