What Are the Relationships Between a VPC, a VPN Gateway, and a VPN Connection?

A VPC is a private network on the cloud. Multiple VPCs can be created in the same region while they are isolated from each other. A VPC can be divided into multiple subnets.
A VPN gateway is created in a VPC and is the access point of a VPN connection. One VPC can have multiple VPN gateways, and one VPN gateway can have multiple VPN connections.
A VPN connection is created for a VPN gateway and connects a VPC to an on-premises data center (or a VPC in another region).

The number of VPN connections is irrelevant to the number of local subnets or the number of customer subnets. It is only related to the number of on-premises data centers (or VPCs in other regions) to be connected to your VPC. The created VPN connections are displayed in the VPN connection list. You can also view the number of VPN connections created for each VPN gateway.