The email reader uses Text-To-Speech Synthesis to read your emails. It scans your email to see what type (gmail or outlook) and reads your current email.
You can just click "Read Open Gmail Message" and it will read your current open email. You can also paste in text that you want to be read. You can also select text on your browser, open up the extension, and click, "Read Selected Text".
You can also change the speed and pitch, as well as the voice of your choice.