Portfolio / Media Grid is an element for Elementor Page Builder.
To get started, add the element Media Grid inside a row in Elementor Page Builder.
Once added you will see the options below in the Elementor sidebar:
Fill out each attribute according to your desired settings for the layout of the grid element. Once that is completed move the categories section:
Once you have added the categories you want to organize your images in move to the Images section:
Add the images you would like to add to your portfolio / grid and fill out the title and appropriate category. You can also add a url to each corresponding item.