Please go to https://takeout.google.com/ you can select or unselect what you want to download. 

If you want to download only your mail, please Deselect everything and then scroll down and select only your Mail. You can also choose to download your Google Drive files.

It will take some time to download from Google's server. Once it's finished downloading, you can download your mail archive into your PC. Please also note that this does not download the attachments that are in your emails. You need to download it if you need those attachments. 

If you want to view the downloaded emails, please use the link below and download the software.