You have created a new block and will be adding this block on every page. The block contains user-specific information and cannot be cached. The block is added to the default.xml with:

What does this accomplish?

What is the connection between product attribute sets and categories?

What will be the result of calling the save() method on a collection instance?

Your module, MyCompany_MyModule, is using the frontName mymodule. You need to locate the class responsible for the frontend path /mymodule/custom.
What file contains the controller class for the frontend path /mymodule/custom?

You need to add a new text attribute to all products in the Magento store. When this attribute is displayed on the
product page, its values must be different depending on the selected language.
Keeping simplicity in mind, how do you add this attribute?