It's an invented word, probably from the word 'Instagram', which was originally based on 'telegram'.
A telegram was one of the first ways of sending a short but immediate message to some one - many years before the digital era.
People occasionally invent similar words with the suffix 'gram' to mean something that you send someone. For example, a 'strippergram' is a service whereby you can send a 'stripper' (woman or man who takes their clothes off to entertain people) to a friend. Weird but true. Then, of course, you have 'Instagram' for sending pictures
'Smell-o-gram' is a message containing a smell. The 'o' part harks back to the 'Smell-o-Rama' and 'Smell-o-vision' movies of the mid-20th century.
You make a delicious bowl of noodles, record the lovely smell on your phone, and send it your friends to make them feel hungry. Good idea, isn't it?