Idea of PowerPoint Icon
It's a letter P with a small section of the straight line in the upper left missing. The stylized P is on a modified rectangle that is drawn to look like a sheet of paper with the upper right corner creased and folded forward onto itself. The P is centered from left to right, and closer to the bottom of the page than the top.
This is a PowerPoint icon. It is available in PNG and vector. Downloading is free for PNGs up to 100x100px.