1Years and months; the passage of time over a long period. Can refer to a long stretch of time or a time span measured in years and months.
年月が経つと、その建物もだんだん古くなった。
As the years went by, that building gradually became old.
年月をかけて研究を続けた結果、大きな成果が出た。
After years and months of research, great results were achieved.
年月を感じさせる古い写真を見つけた。
I found an old photo that shows the passage of time.