In Items, you can choose which items of your post you want to appear in your post grid.
By default, there is a Title and a Featured image in Items.
You can add more items for your posts such as date, title, terms, author and read more button.
You can customize the ordering and styling of items displayed. You can easily drag the items for the ordering.
For each item list, there are content, styling and advanced options.
Settings for each item is different as the content is different. So, for example, if you want to customize the read more button text and customize its style, you can do that by the click on "read more".