Reading this a resource is like cpu and other requirements from pods.
I then don't understand why the documentation then says, that you can create resources with kubectl create -f. Is that not creating pods - and pods is not a resource?
In the second link, the term resource refers to kubernetes API objects, such as Pods, Deployments or Services. You can create those objects/resources using kubectl create -f.
It doesn't mean cluster resources as in CPU, memory, etc. Those resources are the resources that Pods use from the cluster.