Skewness refers to how a distribution "leans". It is important to recognize skewness because it has strong implications in hypothesis testing.
Let's examine three different kinds of skew:
This symmetrical distribution has no skew. The mean exists perfectly at the center.
This distribution is skewed to the right. The mean is pulled to the left from the center.
This distribution is skewed to the left. The mean is pulled to the right from the center.