Take a look to this documentation related to resources in Kubernetes:

You can use resources as described in the article:

To specify a CPU request for a Container, include the resources:requests field in the Container resource manifest. To specify a CPU limit, include resources:limits.

In this exercise, you create a Pod that has one Container. The Container has a request of 0.5 CPU and a limit of 1 CPU. Here is the configuration file for the Pod:

apiVersion: v1
kind: Pod
metadata:
  name: cpu-demo
  namespace: cpu-example
spec:
  containers:
  - name: cpu-demo-ctr
    image: vish/stress
    resources:
      limits:
        cpu: "1"
      requests:
        cpu: "0.5"
    args:
    - -cpus
    - "2"

Additional to your question: Yes it is not gonna run in parallels (multi core threads). But you can show few core for your application in pod and then use multi threads to execute it.

The args section of the configuration file provides arguments for the Container when it starts. The -cpus "2" argument tells the Container to attempt to use 2 CPUs.

The closest answer I found so far is this one:

For a single-threaded program, a cpu usage of 0.1 means that if you could freeze the machine at a random moment in time, and look at what each core is doing, there is a 1 in 10 chance that your single thread is running at that instant. The number of cores on the machine does not affect the meaning of 0.1. For a container with multiple threads, the container's usage is the sum of its thread's usage (per previous definition.) There is no guarantee about which core you run on, and you might run on a different core at different points in your container's lifetime. A cpu limit of 0.1 means that your usage is not allowed to exceed 0.1 for a significant period of time. A cpu request of 0.1 means that the system will try to ensure that you are able to have a cpu usage of at least 0.1, if your thread is not blocking often.

I think above sound quite logical. Based on my question, 100m core of CPUs power will spread across all the CPU cores, which mean multithreading should work in Kubernetes.