It can refer to:
* The physical organ: "Le cœur est un muscle important." (The heart is an important muscle.)
* The center of something: "Le cœur de la ville" (The heart of the city)
* The core or essence: "Le cœur du problème" (The heart of the problem)
* Love and emotion: "Avoir le cœur brisé" (To have a broken heart)
It's a versatile word with many meanings depending on the context.