The ratio of Omega 6 to 3 needs to be below 4:1 to be a good source of Omega 3, and hemp hearts are at 3:1, so they're listed as a good source of Omega 3.

Flax seeds are even better just for Omega 3 at 1:3, but hemp hearts have other benefits, like more protein, which is why I called them out. That said, I eat a fair amount of flax seeds as well.