Cheerful
Jovial, Warm Weather
noun, な adjective
If you have a sunshine spirit, you're probably a really cheerful and jovial person.
陽気 can also refer to warm weather. (Technically it refers to weather or climate in general, but these days people associate it with warm, sunny weather because of its kanji.)
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
コウイチ君は本当に陽気な男の子ですね。
Koichi is a really cheerful boy.
今日みたいに温かい陽気の日にはピクニックがしたくなりますね。
A day with warm weather like today makes me want to have a picnic.
うちの家族は貧乏だが陽気だ。
My family is poor but jovial.