I think this quotation provides a perfect illustration of the OP's confusion. A plane does not fly "at 15kts [airspeed]" and then "encounter" air moving toward it. The plane is flying in the moving air, not toward it. A plane flying at a 15 kts airspeed has that airspeed whether it is flying toward, away from, or across the direction in which the wind is blowing relative to the ground.

Many beginners think that a plane turning into the wind will have its airspeed increased as a result of that turn and that a plane turning toward downwind will lose airspeed as a result of the turn, just as a car would. Understanding why these effects do not occur is an essential first step in understanding how an airplane behaves in the wind. Arguing at length that these effects do occur is just a waste of everybody's time. (In principle, this is just another version of the "plane on a treadmill" puzzle: the people who insist that the plane on the treadmill won't be able to take off are mostly the same people who think a plane turning into the wind has its airspeed boosted because of the turn. They are so used to thinking about vehicles moving on the ground that they can't get their heads around the notion that a flying plane has no connection to the ground save gravity (or ground effect when very low).)