the definitions of financial words?

Hello, I am a student studying financial system.
When reading a book written about financial system, i came across many financial words that I’ve never heard of before.
I’ve looked up them in the dictionary but there were no definitions.
So would you please let me know the definition of "Advance"
and "Operational balance" ?

* 1. Bank lends to a customer whose spending leads to an increase in ‘advances’ at the expense of operational balnces.

It would be perfect if you let me know the exact meanning of this sentece as well.
Thank you!

Have you tried google? I am a firm believer in finding stuff there. You may even find a clearer definition of your sentence.