When I'm Sixty Four. A Beatles song written by Paul McCartney, credited to Lennon/McCartney and released on Sgt. Pepper's Lonely Hearts Club Band. You can read about it in Wikipedia if you want more history about the song. I like the song. 
I think people put more meaning in songs generally than the writers do both lyrically and musically. We can debate about what this and that means but I think in the end it's best to just enjoy a song for what you get out of it.
Here's the guitar lesson. 
Thanks for your support. :)
Hal Stead

https://youtu.be/55e4Fn8yMZo