There currently isn't a feature to block another player. The screenshot above probably shows a bug that occurred with the system.
If you believe a player is behaving in an inappropriate manner, please e-mail
support@teamlava.com with a screenshot of the inappropriate comment(s) you wish to report or write them down in your e-mail. Also provide your ID and the name and ID of the player you are reporting, if possible, and a representative will be happy to investigate the incident and take appropriate action.