What happens if there are no resources on any node to place a Pod?

If there are no available resources (CPU, memory, disk, etc.) on any Kubernetes node to host a Pod, the scheduler (kube-scheduler) will not be able to assign the Pod to any node. As a result, the Pod will remain in the Pending state and will not be started.

You can see the reason in this state using the command:

kubectl describe pod <pod-name>

It will indicate that there are no suitable nodes due to resource shortages. Until resources are freed or new nodes are added, the Pod will not start.