What it is
VMware Cloud Foundation, usually shortened to VCF, bundles vSphere, vSAN, NSX and the operations tooling into a single product. SDDC Manager knows the dependencies between those components and applies updates in an order that has been tested.
That is the actual point. Run the pieces separately and you maintain a compatibility matrix by hand, and every update becomes its own project.
What it is for
Private cloud in your own datacentre, built from standard blocks with an API in front of them. VCF is aimed at estates large enough that operational effort and standardisation outweigh the price of any single licence.
For three hosts in a branch office it is the wrong tool.
What changed
Since Broadcom acquired VMware, VCF is the central offering and licensing is a per-core subscription. Anyone coming from an older perpetual estate is not renewing the same invoice. That belongs in the planning before the technical design does.