I'm assuming you mean if you use the tools on the page of a hub (not your own) that you are reading. If you "like" a hub and your settings on Facebook are compatible, your friends (and maybe their friends or the public, as well) will be notified that you "liked" the hub and they may visit it.
If you click "tweet," a screen will pop up with a prepared message (which you can edit before sending) that will go to your Twitter followers if you send it.
If you click the"pin-it" button, a default image (normally the first image) from the hub will appear in a pop-up screen for your pin. You will choose which of your boards to put it in and edit the caption that goes with the pin, and then pin it.
For any of these buttons to work you will have to already have an account set up with Facebook, Twitter, or Pinterest. By using these buttons you are helping to promote the hub, which the author of the hub will much appreciate. You may also be helping the hubbers who are featured at the bottom of the hub, right above the comment section.