How do you make something complex into a simple idea that can be communicated? One technique is to leverage schemas, or mental models, that people already have in their heads.
How do you describe a "pomelo" to someone? You could go into a detailed description of how it's a large citrus fruit with a yellow, thick rind, that tastes anywhere from spicy-sweet to tangy and tart, depending on ripeness. Or you could just say it's a supersized grapefruit with a soft and thick rind. In the second example, you're leveraging the schema that we all have of a grapefruit. It's so much easier for us to grasp this new concept. We already have associations with a grapefruit, and now this concept of pomelo will inherit these associations.
People that pitch movies in Hollywood often use schemas to communicate their ideas quickly and effectively. "Speed" was pitched as "Die Hard on a bus." "13 going on 30" was pitched as "Big for girls." "Alien" was pitched as "Jaws on a spaceship."