0-playbook.yml

---
- hosts: localhost
  gather_facts: false

  vars:
    my_python_script_content: |-
      import sys
      sys.stdout.write('test')

  tasks:
    - name: create my python script right for this example
      copy:
        dest: /tmp/test_script.py
        content: "{{ my_python_script_content }}"

    - name: run my script, register result
      script: /tmp/test_script.py
      args:
        executable: python3
      register: run_script

    - name: Show raw registered var
      debug:
        var: run_script

    - name: Eventually assign the exact result to a relevant var
      set_fact:
        my_specific_var: "{{ run_script.stdout }}"

    - name: Use that var in whatever task
      debug:
        msg: "My wonderful python script has returned the following result: {{ my_specific_var }}"

1-execution.txt

$ ansible-playbook 0-playbook.yml 

PLAY [localhost] ****************************************************************************************************************************************************************************************************************************

TASK [create my python script right for this example] **************************************************************************************************************************************************************************************************************
changed: [localhost]

TASK [run my script, register result] *******************************************************************************************************************************************************************************************************
changed: [localhost]

TASK [Show raw registered var] **************************************************************************************************************************************************************************************************************
ok: [localhost] => {
    "run_script": {
        "changed": true,
        "failed": false,
        "rc": 0,
        "stderr": "",
        "stderr_lines": [],
        "stdout": "test",
        "stdout_lines": [
            "test"
        ]
    }
}

TASK [Eventually assign the exact result to a relevant var] *********************************************************************************************************************************************************************************
ok: [localhost]

TASK [Use that var in whatever task] ********************************************************************************************************************************************************************************************************
ok: [localhost] => {
    "msg": "My wonderful python script has returned the following result: test"
}

PLAY RECAP **********************************************************************************************************************************************************************************************************************************
localhost                  : ok=5    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0