Escrow is when a "middle man" (a reputable, trusted third party) is used to a conduct a transaction between a buyer and seller. In your case, since you are looking to buy BTC, after reaching an agreement with a seller, the seller would send the BTC to the escrow agent. The escrow agent would notify you that he has recieved the BTC and you would then send your payment to the escrow agent. Once the escrow agent has recieved your payment, it would be forwarded to the seller and the BTC would be sent to you.
Ok thanks I am googling about it now.
But in the case of BTC who would the escrow agent be?
Is there some online website or do we both have to choose a person we Both feel will not run off with both our moneys or what?
You and the seller would have to look through the Currency Exchange portion of the forum to find someone you both trust, based on the recommendations of others. (John K has been recommended quite a bit.) Don't just let the seller pick an escrow agent that you don't trust or feel safe with. You should be able to work out a deal in the Currency Exchange portion of the forum, without using another website.