In 3D computer graphics there is a time to build a product or scene and there is a time to make it ready for the type of media it is used on.
The product or scene is first build in virtual space, in the computer so the speak. To get the picture in a magazine, video, movie, on television or website, you'll need to get the picture rendered, calculated for the right dimensions required. This can take some time, if the picture holds reflections of water or windows reflections, this will take longer than the rendering of solid colors.
An animation is a sequence of those pictures, in 3D and video we call these frames. The amount of frames is based on how long the animation will be. For instance a 1 minute movie will hold about 1500 frames/pictures (25 frames per second). A follow up of these pictures give you an animation.
So you'll need powerful computers, which we have.
Is the animation even to extensive for us, we rent the computer power at a render-farm.
What a render-farm? Yes, but without the cows :-) only computers.
What is 3D and what can it do for you?
3D Project preparation
What is 3D