Info graphic is a visual representation of your information or data, in simple sense if I describe an entire article in writing content but on the similar sense if it is a graphical image in which you describe every step or ways in diagrams charts form so its called info graphic.
Example: If you have two Air conditioners with different characteristics. Now if someone say to write an article on both air conditioners features comparison so that sounds easy for almost people's but If I say I don't need content right now I just need an image doesn't matter their size (Height or width) simply put your complete features comparison on that images in the shape of product images, highlighted features, pros and cons etc even can put content on image for better understanding.
Info graphics now become the trend of online marketing and Good from SEO perspective.
Hope the answer!