Hi Dana,

The symbol $x$ stands for an unknown number, the symbol $y$ stands for an unknown number and the symbol 2 stands for a known number, two. In algebra when two symbols that stand for a number are placed beside each other the operation between them is taken to be multiplication. Thus $2xy$ means 2 times $x$ times $y$ or said algebraically $2xy = 2 \times x \times y.$ If you want the operation between two symbols to be something else, like plus, you have to say it explicitly. Thus for $x$ plus $y$ you need to write $x + y.$

I hope this helps,

Penny