So, an upload speed of 10Mbps indicates that you can upload ten megabits (or ten million bits) from your device to the internet every second. So, let's say, for example, that your home Wi-Fi upload speed is 10Mbps (megabits per second). Your device uploads data to the internet so the other person on the call can see and hear you remotely. The upload speed refers to the speed at which your device can transfer data to the internet.
