有句英文不理解在文中啥意思

有句英文不理解在文中啥意思
根据上下文的意思情帮忙解释一下“Here is one more;and one and two make three.So here are three chickens”这句话在文中的含义,谢谢!
The son smiled and said, "Father ,I have studied a science which can make me prove that these two chickens in the dish are really three chickens."
"Well ,"said the father ,“this is something I would very much like to know"
“so would I,”said the mother."How can you prove there are three chickens in the dish?"
“Oh, that's not difficult.There are two chickens on the dish,”said the student.He took one of the chickens in his hand and said,“Here is one more;and one and two make three.So here are three chickens.”
最后一个双引号里面的句子在文中是个啥意思啊?