A computer that’s not where you are.
It used to be that if you wanted to use a computer to compute something, you needed to buy a computer.
The cloud computing model allows people to be computer renters instead of computer bvuyers. You can now buy "compute resources" on a cluster of computers that is managed by someone else (namely, Amazon, Google or Microsoft)
This "cloud" rental model has the same huge advantages that housing rental does. It's not your responsibility to upgrade the appliances or fix the leaky pipes. And computers only degrade in value so there's no chance of you selling your server hardware for more in 10 years.