Verse I: Stairway to Heaven
“And she’s buying a stairway to heaven.”
A stairway to heaven is, of course, a metaphor – a way for us to reach heaven from earth. The same idea is mentioned in a well-known biblical teaching, in which the “stairway” could be a reference to Jacob’s Ladder (in which Jacob has a dream of angels climbing a ladder, thus ascending to heaven).
The lyric of the woman “buying” the stairway is a statement on materialism and the idea that you can buy your way to salvation (which was a real practice at one time called “Indulgence”). Heaven, in this case, could also be a metaphor for ultimate happiness. “She” is buying her way to having it all. But, as with many classic songs, the lyric could also just be a very broad metaphor used to create speculation (you could, of course, take it to mean anything you want).