Loaded latency measures ping during three stages, giving you a convenient, easy to use way to better understand your network experience. These three stages are:

• Idle Ping: This test at the beginning of your Speedtest measures the response of a request on your network as if it is not in use.

• Download Ping: Latency is measured while the download test is in progress to see how it is affected by download activity on your network, like a household member downloading a large game while you’re trying to work.

• Upload Ping: Latency is also measured while the upload test is in progress to see how it is affected by upload activity on your network, like someone on your home network uploading a year’s worth of photos.
  

Source: https://www.ookla.com/articles/introducing-loaded-latency