How to create a directory using Ansible

How do you create a directory www at /srv on a Debian-based system using an Ansible playbook?

You want the file module. To create a directory, you need to specify the option state=directory :

- name: Creates directory
  file:
    path: /src/www
    state: directory

You can see other options at https://docs.ansible.com/ansible/latest/collections/ansible/builtin/file_module.html