VCESat is the typical voltage when IB flows. in this case, if you souce 50mA into the basis, the voltage between C and E is assumed to be 1V. But you won't be able to get 50mA out off your Arduino. Additionally, you should have a resistor in series from Arduino to B.
The VCESat multiplied with the current IC is about the Power dissipation...
Maybe it's useful if you think about MOS transistors. They need (nearly) no current for control and have e very small RDSon wich means when the transistor is in on state there will be less voltage at the drain than at the collector of that old-fashioned 2N2222. And you don't need any resistor between Arduino and the gate electrode. Please see the image below.
