If you walk into a slight breeze the apparent wind (what you feel) is stronger, if you turn and walk downwind it feels calm. That shows you that apparent wind on the ground depends on adding up the actual windspeed with the groundspeed. Windspeed 3mph, walking into it at 3mph apparent wind is 6mph, walking downwind at 3mph apprent wind is 0mph. The difference is quite easy to feel on your face so long as you know which directions is upwind!
Remember you are adding vectors - speed plus direction. You can draw it out very easily. I would have pointed you to the Wikipedia page but it has a horribly complicated diagram for somthing that is very simple. Sailing websites might have something simple showing how to draw it as apparent wind is important when sailing.
If you are a balloon in the breeze it has no concept of upwind and downwind, it simply gets blown along in the breeze. If the breeze is 10mph northerly you watch the ground sliding past at 10mph as you get blown to the south and there wil be no apparent wind. If you swap the balloon for a plane then your power settings and pitch will provide an apparent wind, but the real wind will still be blowing you south at 10mph.
BTW vector drawings can also show how to deal with crosswinds, and with tides!