For Dumb LED strips: Every 3 LEDs will have its own current limit resistor;
If it's a 12V strip then it will have resistors.
One more question if you don't mind;
To drive one of these LED strips, I need to use a NPN transistor. However, I am not sure which transistor to choose and the resistor to connect its base.
5M of LEDs needs about 2A so you should really use MOSFETs for this.
I reckon the resistor should be something like that for 5 Meters;
5* Hfe / (1.3 * 2)
where 5 is the switching voltage from digitalOutput and 2 is the load current drawn by LED strip
There's no need to mess around with Hfe calculations if all you want is to switch stuff on/off with a BJT. Just use 220 or 330 Ohms, whatever's handy. That will fully turn on just about anything.