Correct. We are touching on vector "arithmetic" here but because such a mathematical title will scare the majority of people away unless they have a grounding in Mathematics, Physics or Engineering, all sorts of devices have been invented to prevent people from realising what they are really doing but enabling them to get the answer that they require.
Basically, for those who don't already know there are two types of quantity: scalar quantities which only have magnitude, like mass or volume or time and so on and vector quantities which have both quantity and direction. The most important one for pilots is velocity, because we need to know in what direction our aircraft will travel and at what speed over the ground - a vector quantity. The answer is the sum of two other vector quantities: these are the direction that the aircraft is pointing plus the speed at which it is travelling through the air and the speed of the wind and the direction that the air is travelling. When two vector quantities are added we need to take into account the directions of these vectors as well as their magnitudes.
Think of it another way: the aircraft is moving through the air in a certain direction at a certain speed. The air itself is also moving at a different speed and in a different direction, and it is the combination of these quantities (the result when we add them) which gives us our heading and groundspeed.
Now pity our poor groundborne bretherin, the boating fraternity. When they do similar sums they have to take into account the speed and direction of their boat, the speed and direction of the wind and the speed and direction of the tide! No wonder our forebears got frequently "uncertain of their position" before Mr. Harrisson invented his seagoing clock to enable them to work out their longitude!
P.P.