How KiCad uses the term "component"
At 1/17, this page was a bit dated. The KiCad community seems to have moved on to using the term schematic symbol for what it once called a "component". A good thing, I think- "component" could be understood too many ways.
If you decide to delve into the .net file, and possibly others, you may see the word "component" used a bit more broadly. There's no harm in looking inside the system's files, but it is an "advanced" pursuit, and you'll have to risk thinks like the less strict use of "component".
The rest of this page not terribly important
The rest of this page is not terribly important, now, but I am leaving it in case you are using an old version of the software, or need "grist" for your "mill" of coming to understand KiCad after you have digested what is at schematic symbol.
The unimportant stuff…
I think the greatest stumbling block I kept tripping over when I was new to KiCad is the very specific use that the word "component" was restricted to.
To me, "a component" is something I can hold in my hand, or something depicted on a circuit diagram, aka schematic, or one of the "bits" provided for on a PCB design.
Not so KiCad! And I will try to be similarly narrow in my use of the term. (At 1/17, I am trying to replace all my old references to "component" with the more satisfactory "schematic symbol".)
As far as KiCad is concerned, a component is something depicted on a circuit diagram, aka a schematic.
(For the more general idea, I will use the word "device".)
Components can be simple symbols for a resistor, complex symbols, e.g. this one for a particular microprocessor….
(The screen capture process degraded the resolution of that somewhat. In KiCad it is crisper… and you can zoom in, anyway.)
Be sure to see my page on schematic symbols, already mentioned. Underdtanding the precise meaning and use of "schematic symbol" is important to your happiness in the KiCad world.