季節 is composed of two kanji, き and せつ, however, both of them mean 'season' when translated to English. Though I'm aware that 季 originally referred to the seasons of the year and 節 was initially used to refer to segments of bamboo, both kanji have taken the meaning of 'season'. As near as I can tell, 季節 is the common word to refer to autumn, winter, summer, and spring, but 季 is still in use. Would anyone be able to clear up the appropriate usage of 季 versus 季節? Is there a distinction in connotation between the two? Is 季 used on its own, or merely as a component in combination kanji?
Although 季【き】 and 節【せつ】 both can mean 'season' within various compounds, they are not used on their own to mean 'season' at least in modern Japanese. You always have to say 季節.
Many Japanese compounds are made of two kanji with similar meanings: 危険 (danger + danger), 豊富 (plenty + plenty), 永久 (eternity + eternity), and so on. In most cases, you cannot just pick one of these kanji individually and use it as a meaningful word in conversations.