Answer:
Step-by-step explanation:
A functional requirement describes what a software system should do, while non-functional requirements place constraints on how the system will do so.
Let me elaborate.
An example of a functional requirement would be:
A system must send an email whenever a certain condition is met (e.g. an order is placed, a customer signs up, etc).
A related non-functional requirement for the system may be:
Emails should be sent with a latency of no greater than 12 hours from such an activity.
The functional requirement is describing the behavior of the system as it relates to the system's functionality. The non-functional requirement elaborates a performance characteristic of the system.(stack overflow)