Also to know is, can I play NTSC games on PAL ps2?
Yup - a pal PS2 can play NTSC games perfectly, the GSM just switches into the appropriate mode. Issues only arise with NTSC PS1 games as the timings are hardware dependent on the PS1 side.
Similarly, what is PAL version of ps2? PAL - Phase Alterning Line - is in short the European standard for analog TV systems. So if you have a PAL Ps2 system you won't be able to play games from for example the US that uses the NTSC system instead. Well you can, but not without modifications. There can be few or many differences in PAL vs NTSC region games.
Similarly, you may ask, how can I make my ps2 region free?
The NTSC to PAL conversion can only be patched like 75% of the time, and that involves using ISO's in OPL, not using actual discs. Your best option is to purchase a memory card with FMCB (Free Memory Card Boot) installed on it. You can purchase these modded PS2 memory cards on eBay and Amazon.
How do I know if my game is PAL or NTSC?
PS2 and Xbox 360 games have a little label on the front of the box that indicates whether it's PAL or NTSC. And games with a PEGI rating are intended for a European audience, so those will likely be PAL, although some support NTSC as well.