Everything is fully and completely explained, in terms which mean nothing.
(They ain't perfect, of course.)
"In astronomy, declination (abbreviated dec; symbol δ) is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle. The declination angle is measured north (positive) or south (negative) of the celestial equator, along the hour circle passing through the point in question."
Anyone who doesn't know what declination is, know from reading the introductory paragraph of this scientific Wikipedia article?
Anyone? no? :-)
I rest my case, m'lud.
Why should this be a metric one would want Wikipedia to meet? It's an encyclopedia, not an astronomy course.
Of course, the brilliance of Wikipedia is that if you think you can write a clearer intro, you can do so! You could even add it to the simple language version of the page - https://simple.wikipedia.org/wiki/Declination