Urgency is about how soon it will affect you. Importance is about how much it will affect you.
Urgent and important means it needs to be dealt with immediately and that not doing it (or not doing it well) will hurt, a lot. This is your mortgage bill.
Urgent but not important means an action needs to happen right now, but the wrong move won’t have huge effects. You can screw it up. You can even ignore it. This is your Netflix bill.
Important but not urgent means you can safely ignore it today and you won’t face any consequences. But if you do that every day, it’ll be really bad. This is your kid’s college fund.
And finally there’s not urgent and not important: Not doing the thing will not affect you at all, today or later on. This is checking Facebook.
Urgency and importance are not black and white, of course. There’s no such thing as 100% important or 100% urgent, or 0% important or 0% urgent. It’s all grey and subjective. Still, it’s useful when we make decisions and goals to consider these factors and to be conscious that they’re separate things.