The coconut is surprisingly complicated, a seed and more.
Botanically speaking, a coconut is a fibrous one-seeded drupe, also known as a dry drupe. However, when using loose definitions, the coconut can be all three: a fruit, a nut, and a seed.
The botanical classification doesn’t matter - coconut oil is primarily saturated fat which is what makes it better for you over the PUFA that comes from seed oils.