What is a budget?

It is a plan for using income

Financial plan for a period or long is defined as Budget.( Plan which is based on income )

Hope it helps!

An amount of money that is preemptively set in face of new financial decisions

Explanation:

It certainly is a plan for using income.  But to be more specific, a budget is a set amount of money you plan on using for a certain event.  

For example:

Budgets can be used within every financial aspect of our lives.   If you still don't understand, you can always seek your parents for help as im sure they have a fair understanding and explainatinon for you to understand.  

i think you really need to revive you answer! : d