I’ll play along, such fun...
Hard remainer is a person who voted remain in the 2016 referendum on EU membership but refuses to accept the outcome of that referendum. They refused to accept a soft brexit because they demand the referendum be ignored even though that would undermine democracy. They’re similar to supporters of Trump, who insist the outcome of the recent US election should be ignored and the Republicans should remain in govt even though a majority voted for something else.
What did you think it was? Such people do exist, there were a lot of them in Parliament until Dec 2019, they’re why May couldn’t get her attempts at a deal agreed. There are a number of such undemocratic, tormented souls posting in this thread.
They need to be separated from normal people who supported remaining in the EU but who respect a majority voted to leave.
HTH