Tax Returns

I was interested in tax returns and I am unsure if I get it. I worked in an auditing firm and I was an accounts, I failed to understand what it is, tax returns, for instance, taxes that our office collects let’s say was $70,000 on November, and taxes that our office pays to other provider of services and goods was $10,000. How much do the office claims / pays Tax authority? Would you please explain to me with example, input tax and output tax, because even though I thoroughly read their definition I still don’t get it. Thanks