Yup. The way it spreads is when you start breathing in air that other people have used already.
The masks can be very helpful but if they do not fit perfectly they don't prevent you from breathing in unfiltered air. It is harder to fit them perfectly than many people realize.
One doctor said the main thing a mask does is keep you from unconsciously touching near your mouth/nose area.
It really isn't rocket surgery. Watch a YouTube video or two on how to properly put on *and* remove masks. Practice it a couple of times.