The information below is applicable to both Vagrant Ansible provisioners:
ansible, where Ansible is executed on the Vagrant host
ansible_local, where Ansible is executed on the Vagrant guest
The list of common options for these two provisioners is documented in a separate documentation page.
This documentation page will not go into how to use Ansible or how to write Ansible playbooks, since Ansible is a complete deployment and configuration management system that is beyond the scope of Vagrant documentation.
To learn more about Ansible, please consult the Ansible Documentation Site.