What this actually measures
This times a small download (for ping), an 8MB download, and a 3MB upload against this website's own server, then converts the time taken into megabits per second. It is a genuine measurement, not a simulation - but it measures your connection to this specific server, not your overall "internet speed" the way a dedicated speed test service with servers distributed worldwide would.
Why results can differ from a dedicated speed test service
Results depend on how close this server is to you geographically, how busy it is at the moment, and your own network conditions - a dedicated speed test service (like Fast.com or Speedtest.net) that picks the nearest server from many locations will generally give a more representative measurement of your connection's true capability.
Why ping is measured separately from download and upload
Ping (latency) measures delay - how long a tiny request takes round-trip - while download and upload measure throughput, how much data moves per second. A connection can have excellent throughput but still feel laggy in real-time uses like video calls or online gaming if latency is high, which is why checking both separately gives a more complete picture than throughput numbers alone.
Why upload speed is typically lower than download
Most consumer internet connections (especially cable and many fiber plans) are deliberately asymmetric, provisioned with more bandwidth for downloading than uploading, since typical home usage - streaming, browsing, downloading - consumes far more download bandwidth than upload. Seeing a noticeably lower upload number than download is expected behavior for most connection types, not a sign of a problem.