What happens when you transfer a ERC20 token to a ethereum wallet adress?

So my grandfather got into crypto 2 years ago, he is 66 years old and got in his first ICO (pkn) and invested a small amount of 100$

After the initial ICO, he tried to follow a guide to transfer his tokens on his ledger and transferred them to a new ETH account instead of a erc20 account. I told him i would try to find a answer if he had definatly lost them or if theres a way to get them back? So here i am. Thanks for your responses