Newby Needing help with programming and outputd

Hi all, total newby here, need a bit if guidance if possible.

I've got one of the arduino starter kits and wanted to know how you would produce a small lighting display, can this be used to control for example up to x50 lights? Also for the output to be at 9v, im aware the pcb only goes up to 5v but not sure it can be done using a converter.

Thanks in advance

Arduinos mostly work supplied with 5 volt. Some of them uses 3.3 volt but I guess Your kit is a 5 volt one. They can output 5 volt at a maximum of 20 milliAmperes. An Arduino can turn on and off any device powered by almost any voltage using a driver, driver board, MOSFET transistor etc.
Never expose the Arduino for a voltage higher than its supply voltage, usually 5 volts.
If You want to turn on and off some 50 units You need to either buy a controller having 50 outputs or You need some kind of expansion board.