Execute multiple Ansible tasks with the same list of items
Make separate tasks file make_site.yml:

---
- name: Install apache site conf
  template:
    src: apache-sites-{{ site }}-conf.j2
    dest: /etc/apache2/sites-available/{{ site }}.conf
    mode: 0644

- name: Enable site apache conf
  command: a2ensite {{ site }}
  args:
    creates: /etc/apache2/sites-enabled/{{ site }}.conf


And in your playbook:

- include_tasks: make_site.yml
  with_items:
    - sitea
    - siteb
    - sitec
    - sited
  loop_control:
    loop_var: site