Here you go:
SMC Pentax-A 50mm F2 Reviews - A Prime Lenses - Pentax Lens Reviews & Lens Database
It's the kit lens, so there's a lot of them out there. It's not worth much, maybe $30 on a good day. Good lens, though. Consider it an efficient way to spend your money if the price is right.
Edit: Here's how to identify the lens:
The "
PENTAX-A" marking means it's an A-series lens.
It says
50mm. That part should be self-explanatory.
The "
1:2" is the aperture, meaning f/2. This lens is often mistakenly listed on auction sites as an A 50 f/1.2, which costs about 20x more. (The engraving on that lens would say
1:1.2)
There's only one A-series lens with the 50mm focal length and an aperture of f/2.