Before we jump into GCP, let's first learn what the cloud is:
It is true—there is no cloud: it's just someone else's computer. With the cloud, what we are actually doing is accessing resources and consuming services that are hosted on someone else's computer. If we want to be more precise, the cloud is a pool of computers.
Now, let's look at a more accurate and professional definition used by Google that comes from the United States National Institute of Standards and Technology (https://csrc.nist.gov/publications/detail/sp/800-145/final):
"Cloud computing is a model for enabling ubiquitous, convenient, on-demand network access to a shared pool of configurable computing resources (for example, networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort...