A Primary Group is a construct in Financial Services Cloud that allows you to define the main group for a client. You can use Primary Group to roll up financial data from all the financial accounts that are related to the client or the group. This way, you can get an accurate summary of the client's financial data regardless of how often they change households. Verified Reference: : Salesforce Financial Services Cloud Implementation Guide, page 69.

Explanation
Financial accounts management is a Salesforce Financial Services Cloud feature that enables financial advisors to track and manage client accounts. A financial account is any account managed by a financial institution, such as a bank, an insurance company, or an investment firm. Financial Services Cloud supports many kinds of financial accounts, such as checking accounts, savings accounts, mortgages, credit cards, investment accounts, insurance policies, and more3. Financial advisors can use Financial Services Cloud to view, create, update, and delete financial accounts for their clients, as well as link them to other objects, such as households, goals, referrals, or opportunities4.
References:
Financial Accounts
Manage Financial Accounts

To build the required sharing model for sensitive deal data, the consultant should use the Financial Deal object to capture the deal data and use restriction rules to block user access above the banking associate in the Role Hierarchy. The Financial Deal object is a custom object in Financial Services Cloud that allows you to track and manage complex deals that involve multiple parties, products, and stages. You can use the Financial Deal object to store sensitive deal information, such as deal name, amount, status, or participants. You can also use restriction rules to limit the visibility of Financial Deal records based on criteria such as role, profile, or ownership. Restriction rules can override the organization-wide default sharing settings and block user access to records that they would otherwise be able to see through the Role Hierarchy or other sharing mechanisms. Verified Reference: : Salesforce Help Article 1 : Salesforce Help Article 2