One of the sections within the Know Your Client area of contact overviews is the Banking Information section, accessible by clicking the "Financials" tab at the top of this section:
To add any information here, click the Add button in the Banking section. You'd then see the below:
There are several pieces of information you can track here that, after completion, might look like our original example above.
You can add additional Banks using the method discussed above. Also, you can edit or delete existing banking information using the Actions icon to the left of the Bank Name.
Note that you can create Custom Exports that include any or all of these fields.