Any Sanskrit hackers here? Can someone please explain to me the meaning of the vedic hymn titled Mantra Pushpam?

The hymn can be found here, amoung many other places.

http://www.astrojyoti.com/mantrapushpam.htm


In fact, its meaning is also available at many places and can be found here:

http://www.vedarahasya.net/mantra.htm


However, all the websites that provide translations for the hymn offer an abridged version that almost reads the same, "That one who knows the flowers of Water, he becomes the possessor of flowers, cattle and progeny," and so on. None of the websites provide:

1. Any context as to what the significance of the mantra is; and
2. A word to word translation of the mantra.

Without any context, the literal meaning sounds ridiculous. I'd be delighted to get some help on parsing this.