The song "Immature" by WINNER talks about the struggles of growing up and becoming an adult while still feeling young at heart. The lyrics express the feeling of not being ready to fully embrace adulthood, with the singer feeling like they are still a kid despite their age. They talk about their lack of responsibility and the desire to have fun without worrying about the future. The song also touches on the pressure to mature and the reluctance to let go of youthfulness. Overall, "Immature" captures the conflict between growing up and holding on to the carefree attitude of youth.