you can't just connect a laser diode directly to an arduino.
if the laser module you have has 2 wires coming out, that is likely to be closer to 3 volts, than 5 volts (many small, low powered laser modules are 3.3VDC).
If you aren't looking for speed in on/off (under a few Hz) then you should be fine. There is a small and inconsistent delay in that style of laser driver - which is basically just a current and voltage regulator. That may also put too much draw on your Arduino, current-wise.
If you are looking to gain high-speed control, then you will need to look into a modulated laser driver. Those drivers keep the laser diode powered, but just below the lasing threshold, which keeps it "warmed-up" and gives it a nice fast response. modulated laser drivers also can't be powered from an Arduino, too much current.
Here's an example: AixiZ
that's a great starting point as far as lasers are concerned. not dangerously strong, IR filtered, totally self-cooling, and the modulation is probably in the 5KHz range.
Of course, use caution with ANY laser. And I would also STRONGLY recommend goggles with anything that was advertised over 5 mW (yes, FIVE MILLIWATTS) -- Especially the cheapo pointers. While their visible component may not seem blindingly bright, the cheaper lasers do not have IR filters (and neither do our eyes, btw) and often the crystals aren't properly aligned, which causes them "leak" IR. LOTS of IR. So while your laser is listed at "<5mW" that is not measured individually, that is what it is designed to measure at. It takes a lot more than 5mW of IR laser power for a crystal to convert that IR into 5mW of visible green light.
You only get 1 set of eyes... be careful.