Answer:
Like many organic compounds, the names of fatty acids such as omega-6 and omega-3 contain numbers that are used to describe the position of certain features of the molecule. In the case of omega fatty acids, the numbers 3 and 6 tell where the final carbon-carbon double bond is located. The numbers tell how many carbon-carbon bonds away from the carboxyl group this bond is.
Omega-6 fatty acids are generally regarded as unhealthy when eaten in larger quantities than omega-3 fatty acids because they interfere with the omega-3's functions in the body.