From your turnover you need to pay for your business expenses. What is left is your profit.
After selling some of your products or services on Silvatree you have used up some of your spare capacity and therefore increased your turnover. This extra turnover can be measured in Silva. Your normal business isn't affected.
When you use the extra Silva to pay for some of the business expenses you would ordinarily have paid with sterling then the extra cash you have conserved in your business is seen as increased profit.