Right now some people might see Follow where Subscribe used to be. Follow works the same way Subscribe does. It's a way to see public updates from the people you're interested in.
What does it mean to follow someone or a Page on Facebook?
How do I follow a profile or Page on Facebook?
How do I change who can see the people, Pages and lists I follow on Facebook?
Manage your Followers
Who can follow me on Facebook?
How do I post public updates to people following me on Facebook?
When to create a Page or turn on professional mode for your profile
How to block someone's profile on Facebook