I know the other person balanced it for you but I'll go in a more depth explanation.
This is a single replacement reaction. You want to know how I know this? You are basically do AX + B -> AB + X. In essence, you replace with Anion (Negatively charged ion) and replace it with the other anion.
In this equation, your anions are Chlorine and Fluorine. By replacing Chlorine with Fluorine, you get Sodium Fluoride instead of Sodium Chloride. You replaced the Cl with the F.
So, if the products weren't listed, I would still know them. I replace Cl ith F and the products would be NaF + Cl2. Since both Fluorine and Chlorine are diatomics (that only occur in pairs of 2 in nature), they will have a 2 subscript beside them when they are by themselves.
Hope this helped.
