Feminine and masculine articles rule in French. They dictate the adjectives and the whole meaning of a sentence.
I always tell my students it is IMPERATIVE to learn the article with each new word.
If you learn the word balle, it is UNE balle.
( btw, the picture in the video is not un ballon, but une balle, however they had no picture of a balloon so I messed up. Pretend it's a red balloon :P)