Typically a WBS consists of 3 levels:
- Level 1, which is very high level, including generic tasks, such as Programming.
- Level 2, which is more granular than the Level 1, including less generic and more specific tasks, such as Backend Development.
- Level 3, which is the most granular and very specified, such as Interface Development of the Backend.
It is important to note that the WBS is not a project plan, it just gives the person a decent idea about the project.
Too much detail in your WBS and you'll run into the risk of making it unreadable, too little detail in your WBS and it can become useless.