Follow the steps to know how to import Google Takeout data easily:
Step 1. Visit Google Takeout.
Step 2. By default all options will be selected. If you want to import only Mail, then click Deselect All and only select the checkbox of Mail option.
Step 3. Choose File Type, Frequency and Destination Path as shown and click Create Export.
Step 4. Check your Gmail account from which you have logged in Google Takeout. You will receive a mail regarding Download Archive. Click on it and download the same on your system.
Step 5. If you have selected file type as .zip, then you will get the .zip folder. Right-click on it and extract all the files from the same.
Step 6. Click Takeout >> Mail >> MBOX files.