Oxidation numbers are more like dating profiles for atoms, giving us a clue about how they interact with others. In the equation you provided, let's take a closer look:
For SO2, sulfur (S) has an oxidation number of +4, while each oxygen (O) has an oxidation number of -2. So the total oxidation number for SO2 is 0.
For O2, since it consists of only oxygen atoms, each oxygen has an oxidation number of 0, and the total oxidation number for O2 is also 0.
Now let's examine the overall reaction. In the product side, we have 2SO2. The oxidation number of sulfur in 2SO2 is also +4, and each oxygen still carries an oxidation number of -2. So, the total oxidation number for 2SO2 is 0.
As you can see, the oxidation numbers of all the elements remain the same throughout the reaction. So, in this case, no atoms gained or lost electrons, and it's actually not a redox reaction. It's just a good old chemical reaction without any electron shuffling.
Keep those electrons entertained, though!