Not quite sure what exactly happens, but the Erase option should do something like overwriting the data that used to be on the disk.
When formatting a disk, typically only the partition tables are reset and the disk would look empty.
The data, as in the bytes that make up the files, will typically remain on the disk and can therefore typically easily be recovered.
As I said, I am not sure what exactly Erase does.
I would suspect that it just sets all the bytes on the disk to zero.
As explained on the Arch Wiki page, you can use
dd on the CLI to do exactly this.
You can also overwrite with random data for even better security.