A pure, or natural, minor scale, is one that includes all the degrees of the minor scale according to its key signature with no additions of extra flats/sharps. This is different than either the harmonic or melodic minor scales.
So, for example, since the key signature of d minor is just a B flat, the scale would go D, E, F, G, A, B flat, C, D.
Another example would be that the key signature of b minor is F sharp and C sharp, so that scale would follow the pattern B, C sharp, D, E, F sharp, G, A, B.
Happy to help with any of your music questions any time! :) Good luck!
