When I first came across the concept of qualia, they were described as "the redness of red". This pretty much captures what I understand by the word; when I look at an object, I observe a colour. That colour may be "red", that colour may be "green" (or a long list of other options; let us merely consider "red" and "green" for the moment).

The physical difference between "red" and "green" lies in the wavelength of the light. Yet, when I look at a red or a green object, I do not see a wavelength - I can not see which wavelength is longer. Despite this, "red" looks extremely different to "green"; it is this mental construct, this mental colour in my mind that I label "red", that is a quale.

I know that the qualia I have for "red" and "green" are not universal, because some people are red-green colourblind. Since my qualia for red and green are so vastly different, I conclude that such people must have different qualia - either a different "red" quale, or a different "green" quale, or, quite possibly, both differ.

Does that help?

"Quale" is simply a word for "sensation" -- what the word used to mean, before it drifted into meaning the corresponding physical phenomena in the nerves. A quale is the sensation (in the former sense) of a sensation (in the latter sense).