The speeds mentioned in this thread are those over your "local" network, between your wireless router and your computer or other device.
Sony may be asking about the speed of your Internet connection from your service provider. Chances are, that is in the range of 6-12 Mbps, although it could be more or less depending on the service you have chosen.
If the Sony is depending on an Internet connection to download updates or download movies, the speed of your Internet connection will determine how fast things occur.
Your service provider has probably provided you with a utility to measure the Internet connection speed. If not, you could try
Speedtest.net.
The Internet connection speed is almost always a major "choke" point on any home network since your local network is probably capable of much faster speeds than your service is providing.