The Metafields object is an internal Shopify feature that provides users an extra space to store the additional data used in custom apps and themes. The Metafields object is used for the backend data management only and doesn’t affect neither the storefront nor the functionality of the website by default.
You can learn more about the metafields object here.
Our app is a powerful tool to make metafields management process easier, faster and more efficient, but it doesn’t affect the functionality and/or storefront of your website neither.
You can use metafields to store custom attributes for your products, however, you have to customize your theme in order to display them at the storefront.
Shopify's got a special markup language called Shopify Liquid that serves this purpose.

When it comes to metafields usage in terms of custom Liquid code snippets, all you need to know is that the metafields object consists of three main components: 
 1) namespace,
 2) key, 
 3) value. 
Namespaces are used to group different metafields (something like a folder or a logical container), keys are unique identifiers to reference the information stored in the metafields, and values will contain the the data itself.

In order to display the metafield at the storefront with the Liquid , the one should use a certain pattern: 
{{ product.metafields.namespace.key }}

That’s a really important part of the custom functionality development as a slightest mismatch between the namespace and key combinations used by the custom Liquid snippet and your actual metafields will prevent your metafields from being displayed at the product page. Just a friendly reminder :)

With this said, let’s assume you’ve created a metafield to store additional descriptions for products: namespace will be “custom_design” and the key — “short_description"
In this case, you need to add the following custom line to the product page template file: 
{{ product.metafields.custom_design.short_description }}

as shown in this official Shopify tutorial

Luckily, we’ve got a detailed step-by-step tutorial showing how to add and manage custom product attributes using metafields, some custom Shopify Liquid code and our awesome app.
That’s a pretty nice point to start with metafields usage, we believe :)