For the euro area, it would basically mean increasing the number of current deposit accounts offered from around ten thousand to between 300 and 500 million.
A CBDC of this nature would enable the central bank to register transfers between users, thereby providing protection against money laundering and other illicit uses (or those considered illicit by the rulers of the day), depending on the degree of privacy granted to users. These are just two of the many ways to design a CBDC.