I need to block my opponent's vertical threat in the leftmost column, where they already have two Os (at 0,0 and 1,0). By placing my X at 2,0, I prevent their win. Additionally, this move is strategically strong as it sets up a potential diagonal win for me from the bottom-left (2,0) through the center (1,1) to the top-right (which would be my next move at 0,2). This creates a dual threat situation where I'm both defending and setting up my own winning opportunity.