Lyric discussion by DrBubble 

Cover art for Roots, Rock, Reggae lyrics by Bob Marley and the Wailers

The part where Bob says "we're bubbling on the Top 100" is his recognition of making the R&B musical charts outside of Jamaica. I think BMW also made some Rock charts, too, with Rastaman Vibration. A lot of people didn't think any band from the Third World would ever make such fame and money, etc.

Bubbling is the term used for that rhythmic sound reggae keyboard players make.

Song Meaning