One of the menu options under the Contact Overview menu that is accessible when within a contact record is the Know Your Client section of the contact record:
After clicking Know Your Client, you'll then see the Know Your Client area for the contact and can begin filling in your applicable information for them.
Here, let's look at the Bank Information section of this page:
If no data has been entered here, it will be blank as above. To add data, just click the Edit button in the top right corner of this section. You'll then see the below:
There are several pieces of information you can track here that, after completion, might look like the below::
Note that you can create Custom Exports that include any or all of these fields.