If you’ve already blocked someone on Google and you decide to unblock that person fine you can do it.
You can actually restore that person back to the state he or she was in before you applied the block, to that you need to follow this simple steps.
1. First sign into Google plus account with your email and password
2. Click or tap ‘Settings’ at the top of your Friends list
3. Highlight ‘Blocked’ (to do that place your cursor at blocked, press hold and drag) along the left side of the dialogue box
4. Now find the person you’ll like to unblock, and highlight his or her email address.
5. Click or tap ‘Unblock,’ and then click ‘OK’
You’re done, now instead of the person seeing only your public profile, that person will also see your friends profile, can contact you via Goggle hangout, you also get to see the person’s feeds or things shared, the unblocked someone can even alert you or mention you in any post that is shared in any Google related platform like Blogger or Google plus, in Facebook it’s called tagging, there is a walk around to restricting the access unblocked people have, this way you’ll be charge of your privacy.