If you are not familiar with modules, check out Ansible - Getting Started with Modules.

Typically, the shell, command, or script modules are used to invoke a command on a managed node (e.g. target systems). /usr/bin/python needs to exist on the managed node to use these modules. If Python does not exist, the raw module can be used instead. 

In this example, script.sh must reside on your control node (that's your Ansible server).

- name: my script
  script: /path/to/your/script.sh

The playbook can then be executed using this command.

ansible-playbook playbook.yml

The following should be produced.

TASK [my script]
changed: [server1.example.com]

By default, no stdout is printed. The debug module can be used to print output to the console.