It does mean jeans, but there’s also a play on words in the bridge and last chorus it seems. They say “청춘은 바로 지금” which means youth is right now. It relates to jeans because if you take the first syllable of each of the words, you get jeans (청바지).
Disclaimer that I’m not that good at Korean, this is based off other sources that I’ve seen list 청춘은 바로 지금 as a pun in songs and other art forms
