In layman is (easy to explain) terms?
need more clarification: ''Euribor® is the rate at which euro interbank term deposits are being offered within the EMU zone by one prime bank to another at 11.00 a.m. Brussels time (''the best price between the best banks''). It is quoted for spot value (two Target days) and on actual / 360 day basis''....... l just do not get it
Primarily because l work for an auction company that will sometimes give advances for customers who will sign a promissory note (for no more than 60 days) with us quoting the euribor rate. We are not a bank though we are acting as a bank. What purpose would this serve?

Its basically a lending rate, obviously while ur promissory note is against goods sent u r theoretically at risk if the interest rate changes during the period. If its in Euros then that is not so bad as u would probably not move the funds at all.
If however, u r going to receive a different currency against ur selling price in Euros then u have an interest rate differential between the two currencies, which could change before u receive the funds. If that is the case what u r doing is hedging the currency exposure.
I.E. said customer has agreed to pay 1mio euros in US USD is so 1.355mio usd is u hedge buy selling 1.355mio usd is & buying 1mio euros when the client sends his funds in u deliver the usd is to ur bank & u cover ur hedge thus negating the exchange risk involved however, because we have this interest rate differential u will be receiving & paying interest rates on ur hedge position while the client is just receiving the interest on his 1.355mio usd's.
Your hedge position can be moved forward to the receive day so u will pay interest on the usd is you've borrowed from a bank & receive interest on euros you've bought. Now the bank will pay u euribor minus a percentage for its self & charge u Libor plus percentage for the usd is you've borrowed, the differential is part of the risk u run. In some circumstances u will not hedge out to a far date & run what is known as a spot position which needs to be rolled everyday to keep it as spot (2 days hence) this is known as the tom/next & again its the same as rolling it out to a far date, only difference is the cost is smaller at first glance, however, u r in effect paying the spread or difference between the bid & offer every day instead of once, so the percentage earnt by a bank is greater over a given time than one single move. In which case u should be passing on this interest differential to the said client.

If that all makes sense.

Of course the near term interest rates r the ones most effected by the illiquidity caused by the credit crunch which is why its doubly important at this moment. You can lose a substantial amount without knowing until u reach maturity then u suddenly realise the loss.