It seems he's talking about imperialism and how it still continues today.
"Give them an inch, they take a yard; Give them a yard, they take a mile"
This suggests the idea that when you sit back and allow wrong doing say submitting to a national identity card the result is that the financiers will run with that and push even greater levels of exploitation with say a forced identity chip.
Another example is if you buy a shirt that was made through slave labour in China expect the financiers to exploit your children in the same way in the future.
Unlike most of Marley's song which embody a strong sense of hope and a willingness to fight back this song is a hopeless cry.