Hi I'm looking at buying a home and the MLS listing Status was at A this morning and changed to B. I found a definition of the codes:

BACK-UP OFFERS ARE BEING TAKEN. The seller/lessor is soliciting
Back-up offer(s) through the MLS. The seller/lessor has accepted a contingent
Offer. A second offer would be a back-up offer and would become the accepted
Offer only if and when the first agreement is cancelled.

What does this mean exactly??

A contingent offer means that the seller accepts the offer but there are other requirements need to be made by the buyer. Such things as acceptable financing, they might be required to have a contract to sell their current property or any number of other factors.

Basically it means that both parties have agreed... now they need to hammer out details.