Follow the instructions below on How to add product categories and subcategories to the main menu in PrestaShop 1.7?
First of all, open your PrestaShop dashboard. On the left side choose your catalog section and click on the categories button.
Here we have to click on the add new category button.
Here we have to fulfill our details like category name, Description, Meta Title, Meta Description, and Meta keywords. After this, we have to click on the Save button.
Step #2 add the Subcategory
So here again we Have To choose our catalog section and click on the categories button.
Here we have to click on the add new category button.
So Enter The Subcategory Name, and select Parent category, Now select the main category in which you want to create a subcategory. After that add the Description, Meta Title, Meta Description, and Meta keywords. Simply click on the Save button.
Now choose the Modules section and click on the Module Manager button.
No simply scroll down and configure the main menu section.
Now select the categories you just added. Now click on the add button and then on the save button.
now let's see if our category and subcategory were added or not. Now you can see our category and subcategory have been added successfully.