Exaptation involves taking an idea that works in one realm and adapting it to work in a different realm. It is akin to repurposing a technology or concept from one use to another, such as in the example of a small African village where a boy repurposed a device used on a bicycle to generate electricity for a windmill that could pump water onto their gardens. This concept emphasizes the act of adapting and moving something from one context to another for a new purpose.