Marketing emails need to be personalized to the reader and filled with interesting graphics. Few people want to read emails that are addressed "Dear Sir/Madam" -- as opposed to their first or last name -- and even fewer people want to read an email that simply gives them a wall of text. Visuals help your recipients quickly understand what the point of the email is.
These metrics give you a high-level overview of how your subscribers are interacting with your campaigns and allow you to compare the success of one campaign to another. If you want to go deeper and see the exact people who opened and clicked your campaign, what links they clicked, etc. you can do so by choosing some of the other reports from the right hand side menu.

First, act as though you’re a prospect making their way to your business’s landing page. Start by ensuring that the links to your landing page are working, wherever they may be — email, PPC networks, sponsored social media posts, etc. Are they driving you to the landing page that they’re supposed to? Does everything look the way you intended on every browser?
If links and looks are set, begin interacting with the page. Abandon it, adjust the window size, convert. Are error messages appearing when they’re supposed to (if, for example, you don’t input all the form’s required info)? Is your CTA button working? If you abandon the page, are you retargeted with ads? When you resize the window, does your landing page respond accordingly?