i am having a small assignment in my cource .The assignment is

Assume you are the DBA of a large international banking concern (sites in three countries). You have just taken over the position and found that there is currently no roles used in the database. What roles do you need to create? Consider job function, location, and any other criteria you can identify.

They are asking the role alone not the code in oracle , so please help me what are the possible roles in bank can be created

since application is running OK without any roles, none need to be added now

You should be asking yourself questions such as:

What are roles? What purpose do they serve (if any)? What are the benefits of having roles? Is it easier to work with roles than without?

Then think about how an international bank (or any international organisation) would use roles. (You were given a hint in the question: "Consider job function, location, and any other criteria you can identify".)