I always see that game developers put every bit of sprites of 1 character into one chart. Why do they do this. Is it part of importing the sprites into the game? I'm a noob.

I think you are asking why they use a standard template and the answer is quite simple. The only way the game can know which tile is which is by it's location on the tile sheet.

If you're asking why to put them all in the same file, it's so you dont have a mess of files.
A character can have many sprites in its sprite set, so to have those together and in order they put them in the same file in a grid like arrangement.
The computer then uses grid coordinates to retrieve them.

From a developer point of view, it also reduces having to bind/unbind textures as often - if you have a sprite sheet that contains all the sprites relating to 'tree's for example then when drawing a scene with many tree's the engine only has to bind the texture once, and the use different texture coordinates to draw the correct textures. Texture Binds are an expensive operation so reducing them is always a plus.