Looks like a young berk sow. There is no way we can accurately judge a pig from a picture especially when there's only one.
Questions you need to ask ...
Why is she for sale?
How many litters has she had?
How many piglets does she wean per litter?
How many teats and how many of those are functional?
Is she careful with the piglets and what are her nesting and farrowing instincts like?
How well does she maintain weight while raising a litter?
Her current condition is a very small piece of the bigger picture
IMO
You can google sow condition charts but she looks ok from what I can see in the picture but there is very little reference.