Playing in column 0 extends my horizontal line with my existing O pieces in columns 1 and 2. This gives me three in a row at the bottom, which is good positioning. While I can't win immediately with this (since column 3 already has an X), it strengthens my position on the left side of the board and gives me more options for future moves. There are no immediate threats from my opponent that I need to block, so this offensive development is my best option.