They're being frozen so they're swapped for the REAL EOS tokens. Read this post on registering your EOS tokens and claiming the new ones after June 1st. If you don't understand it, I'd recommend just moving your EOS tokens to an exchange that supports the swap, like Binance.

Here's the link to the post: https://www.reddit.com/r/eos/comments/7jarzj/how_to_registerclaim_your_eos_tokens_before_june/