If someone is jocular, they are being funny on purpose — making small jokes, speaking in a light, playful way. It is not “hilarious”; it is milder, more like smiling while you speak. A teacher might offer a jocular remark to help the class relax. You would not usually call a stand-up comedian jocular; the word sits closer to cheerful teasing than to a show. It is a somewhat formal or bookish adjective, more at home in writing than in the playground. Though actually, a jocular tone on a serious subject can feel odd, or even unkind, depending on the moment — the word itself does not tell you whether the joke landed.