A website designer is someone who focuses on the aesthetic designing of your custom website development by adding graphics, animations, pictures, videos to it. This aesthetic addition gives the visitors to your website a sense of pleasure. You should know that it is not necessary for the website designers to know the working of the code languages as the website developers do.
But yes, they should surely know how to design an aesthetically pleasing as well as a user-friendly website. They make use of graphic designing software which helps them in designing different layouts when constructing the prototypes for the website. Or simply you can say that website designers are the individuals who control the flow of information and are also responsible for the website analytics.