A Message Template is what you need to send a Template Message!
Message Template
A Message Template is the pre-approved templates submitted in your WhatsApp template manager.
Depending on your subscription, a certain amount of templates can be registered in your template manager.
For more details, please check the article Message Templates
Template Message
Once your Message Template is approved, you can send a Template Message to your customer to initiate the conversation.
For these messages, a transactional fee will be applied. You can find a further explanation on pricing in How do we calculate WhatsApp pricing.