Typically when someone blocks you on a social network, your friendship connection is completely removed. If you would also like to block the person, it is generally possible to do so using their email address.
However, there are some things that you may want to consider before you get to clicking away. Remember first that unfriending someone is much different that just hiding them or unfollowing their posts. Unfriending cuts your connection completely and forever - it's a really big step.
Being unfriended hurts and returning the favor may feel good in the moment but stop to think about the reasons behind it. If you just frequent social networks for personal reasons, then it is unlikely to carry much consequence. However if your profile is associated with your business or professional like, then unfriending may be more serious. What if the person that you've unfriended brings up the issue to a mutual acquaintance? What if the person is still friends with your best friend or significant other? What about the tension and awkwardness if you were to run into each other? What if you need a favor from them in the future?
Of course there is certain behavior that just demands a return unfriending. If the person in question has posts personally insulting comments to you or is generally spreading prejudice or bigotry, then unfriend away! If you noticed that the person only used social media to sell a product of promote themselves, then unfriend them too! If that person is just generally intolerable and you still wonder why you friended them in the first place, then go at it and cut the cord!
It is important to remember that if you are generally unsure about unfriending someone who has done the same to you, then you might want to err on the side of caution and remember that you always have to option to simply hide their posts if they add you back. This is often the best way to proceed if you are not sure what the consequences will be for a return unfriending. Proceed with caution and manage your social media network with care!