1. How to understand Workflo?

WorkFlow in simple: The state of an object changes from one
state to anather with Human activity.
There must Human Activity involved.
Example from agent to operational manager to next higher
manager.

Agents submits a paper to be approved by his operational
manger.
Agents object state is being changed by his operation
manager with some interface/GUI etc.

2. What kind of information goes to Technical Specification for SAP Business workfllows?

While developing the workflows, one has to make use of
interface, methods, data types , reference types etc. The
technical specification should carry about the changes made
in interface, methods, datatypes, etc.