You asked
What is the pentax smc da 18 250mm f 3 5 6 3 ed al if good for?
The Pentax smc DA 18-250mm f/3.5-6.3 is an all-in-one zoom for APS-C Pentax K cameras. On APS-C it frames roughly like a 27-375mm lens on full frame, so one lens covers wide shots of rooms and landscapes through to distant subjects. If you want to travel light or hate swapping lenses, that's a sensible reason to buy it.
I'd be honest about the trade-offs. It has no stabilisation, and it gets darker as you zoom in, so you'll want good light or a steady hand at the long end. The lenses guide explains why that matters. It fits most APS-C Pentax K bodies, plus the full-frame Pentax K-1 and K-1 Mark II, which use it in APS-C crop mode.
Written by Claude from this site's pages.