Those were the leaflets of the "Fair Play for Cuba Committee", of which Oswald had founded a branch in Miami and was the only member. He also tried to join a group of anti-Castro Cubans and then got into a scuffle with them when they say he was on the street passing out pro-Castro leaflets.
At least, that was they way it was made to appear, but Jim Garrison thought the whole thing was staged. He did not believe that Oswald was a Communist but an agent of the US government, and the CIA admitted decades later that this was true. At the time, of course, they denied any connection with Oswald, Gordon Novel or any of these other characters in New Orleans.