If you block a user, that user will not be able to see your questions and answers. You will not be able to see blocked user's questions and answers as well.

<Block>

  1. Tap or Click the options icon (...) on the profile, question, answer to bring up the options menu.
  2. Tap or Click [Block].

<Unblock>

  1. Tap or Click [Settings]
  2. Tap or Click [My account]
  3. Tap or Click [Blocked users]
  4. Tap or Click [Unblock]