Hi, and welcome to the forum. It's Good to "see" you and I hope you enjoy your visits.
Unfortunately, there is no way to block emails on the ipad itself. It is merely a mirror of (and a way to download) what is being sent to your e-mail account on the server.
Depending on the type of account you have, you should be able to go to the settings of your e-mail account on the Internet and Set up filters to block that certain person or address. If all else fails, I am sure your home Internet Service Provider (ISP) may have ideas on how to help you block it. Maybe give them a shout?
Marilyn