There's several different ways of downloading your files to your computer from Google Photos.
The simplest way of downloading an image or video is simply by clicking or selecting it and click download, or Shift+D. You can also select multiple pictures and download them together. There is however a limit to how many files can be selected at once. Which means it can be cumbersome to download all your images this way.
To download your whole Google Photos library at once you can request an export with Google Takeout. This method will ensure you receive everything from Google to your computer. You can find more detailed instructions on how to request a Takeout here.
Once you've downloaded your Zip files you can simply unpack them and find your images. They might however be in an unsorted order. Images might also not contain all information, some data about the images might instead be located in a .JSON-file with a similar name. For example image_123.JPEG is the image and image_123.JSON is a text file containing more information like GPS coordinates, people tags, and timestamps. You can manually write this data to all images, for example with a tool like ExifTool. SyncGP can also help you through all of this, unpacking all the images and writing all the correct Exif data automatically.
A third option is downloading your images through the SyncGP Downloader tool. This can help you download all your images at once, without requesting a takeout or manually downloading the images and videos. You simply log in to your Google account and setup up the download. You'll find all your files locally on your computer once it's done. See more at SyncGP and watch a demo of how simple it is.