The production pipeline is a chart used to plan out the stages of the creation of any media whether it is a video game, movie or TV show.
The production pipeline is generally a linear map that shows the beginning to the end, usually consisting of pre-production, production and post production. Let's focus though on something like a 3D animated feature film
Pre-production consists of the ideas and build up to creation, generally dealing with story, storyboarding, writing, designs and management of the lead-in to production.Budgets and what people will be working on will be laid out.
Then comes production, the meat of the product itself. This will be modelling, rigging and animation as well as texturing, there may be need for some rendering to test things out.
Finally to put it all together comes post production: Compositing, editing, lighting and rendering. All of these tie the animation together and give it a final pass of quality and ensuring the product comes together as a whole.