Flair is that extra thing of interest, or extra things. The frill on the dress, the emotive language that makes him stand apart, the deep description that makes you want to be there, the curly little embellishments added to the corners that others did not think to add. Lacks flair, means is a little ordinary: no such innovations. Has flair means there is something to see, to hear, something that seems innovative, unusal, not there with others. . Like a super-noticable avatar image :)

He is not interesting. He has no skill. https://en.wiktionary.org/wiki/flair

"Flair" is similar to style, fashion, and elegance. "Flair" suggests something good, but something on the surface. It suggests something attention-getting. It suggests something unnecessary, something extra, but pleasing. Bartender A just puts a glass of beer down in front of a customer. Bartender B gives it a push, and pushes it just right. It slides down the bar and comes to a stop right in front of the customer. The beer doesn't get there any faster. However, it is fun to watch. Bartender B has flair. Writer A writes: "King Midas sat down to breakfast. In front of him was a fried fish. When he touched it, it turned into solid gold." Writer B writes: "To his horror, it was immediately transmuted from an admirably fried brook-trout into a gold fish. Not a goldfish, it was really a metallic fish, and looked as if it had been made by the nicest goldsmith in the world. Its little bones were now golden wires; its fins and tail were thin plates of gold; and there were the marks of the fork in it, and all the delicate, frothy appearance of a nicely fried fish, exactly imitated in metal." In my opinion, writer B has flair. However, using plain language, writer A may still be able to tell a good story.

OK, "flair" and "flair for" are different. Philip has answered for "flair for" . I have no flair for languages = no talent, no exceptional skill, no naturalness to doing <something> No flair = not innovative, just usual, His work is good, but shows no particular flair. . You can see that for many things, the meanings are similar.