Apart from the standard roles (such as Admin, Staff, etc.) in Zoho Books, you can add additional roles with different levels of access. These roles are called Custom Roles.
To add a custom role:
Go to Settings in the top right corner of the page.
Select Roles under Users & Roles.
Click the New Role button in the top right corner of the page.
Select the modules and the level of access you want to provide for the role.
Click More Permissions for additional access options.