Aragorn spent literally decades with Gandalf hunting down and interrogating Gollum, among other things, before Frodo even had any clue about what the ring was. Aragorn also knew a Hell of a lot about the overall geopolitical situation that everyone in the Shire was entirely ignorant of. Aragorn was the person giving Frodo the most advice.

But he knows approximately what it does and has like 50 years of experience of hunting the enemy and a whole ass education in the history of the world etc.