What is it?
Blocking another user prevents them from being able to comment on your ads. You can only block a user who has already posted a comment on your ad.
Once you have blocked a user, they are unable to post anymore comments on any of your ads, and to contact you by private message. Likewise, you will not be able to comment on any of their ads or private message them.
How to block a user?
To block someone who has commented on your ad, you need to report their comment by clicking on "report comment", and then tick the "block this user" option.
The blocked user will be told that you have requested not to receive anymore comments from them.
Other users cannot view the list of users in you have blocked.