The primary thing to understand about business capability analysis is that it is about assessing what an organization is able to do. This is assessed in terms of performance gaps and any risks in the capabilities to determine where to invest to improve the overall organization in terms of growth.

Make sure you understand the concept of a capability and the relationship a capability has to the value it creates within an organization. 

Business capability analysis is often used as part of current and future state analysis to help an organization determine where to focus their efforts to achieve their organizational goals and objectives.

Business capability analysis is also used to determine the performance of a certain capability and to assess the risks that exist within a capability.

The final important point to take note of is that business capability analysis is often carried out by using capability maps to visually describe the different considerations of a capability within the context of the organization.