hello, baleares
Think about a river. Water. Flowing down stream at a speed of ten miles an hour. You are on a raft on the river, floating downstream, what is your ground speed? --- how fast are you traveling past the scenery?
Answer, ten miles an hour ground speed. But how fast is your speed through the water? Zero, right? You and the water are moving together, down a lazy river.
Now turn around and turn on the power, head up stream with a good old Evenrude outboard at a speed through the water of twenty miles an hour.
What is your ground speed past that dock?
Did you work it out? I am sure you had no problem. Well, air is exactly the same as water, only a bit thinner.
So plan always if you can, to do your takeoffs and landings into wind. Assume the wind is twenty miles an hour. Your speed through the air could be sixty miles an hour. What would your groundspeed be at touchdown?
Now get set for takeoff. Full power. Accelerate. Groundspeed is now 40 miles an hour. What is your airspeed?
Few basic aircraft have an instrument that gives you groundspeed, a GPS could do that. What matters to the airplane is the airspeed. Neglect not thy airspeed lest the ground rise up and smite thee!
As happened to that Korean airliner at San Francisco.