丰富 (fēng fù) means 'rich, abundant' and is the most general word for describing a large quantity or variety of things like resources, knowledge, or content. It differs from 丰盛 (fēng shèng), which is only used for food/meals, and 富 (fù), which focuses on material wealth. 充实 (chōng shí) is more about a fulfilling, substantial quality (e.g., life, argument).