Heat the olive oil in a large skillet or pot over medium heat.
Add the chopped onions, cover, and cook for about 5 minutes, stirring occasionally, until they have softened.
Add the vegetable broth and barley to the skillet.
Stir well and bring the mixture to a boil.
Reduce the heat to low, season with salt to taste (use more if you're using water instead of broth), and cover the skillet.
Let it simmer for 5 minutes.
Add the broccoli florets on top of the barley. Replace the cover and continue to cook for another 5 minutes, or until the broccoli is crisp-tender and the barley has absorbed most of the liquid.
Stir in the drained and rinsed Great Northern beans.
Continue to heat for 1-2 minutes, or until the beans are warmed through.
Serve immediately.