If you're productive, that means you do a lot — you create or produce large amounts of something. A productive worker makes more widgets than the shirker who keeps sneaking out to gossip and drink coffee.
The word productive often describes a person's capability to do a lot of work, but is can refer to anything that produces a lot. The land in your area might be the most productive in the state, meaning crops grow very well there. Productive can be used more broadly to describe something that produces a positive result. For example, you might have a productive conversation with your mom about your college plans, or you might make a productive investment.