four: the cardinal number 4
This is simply the number four. It counts things the way any number does: four kings, four rivers, four corners, four years, four hundred shekels. The Hebrew has a masculine and a feminine form (the spelling shifts depending on what is being counted), but both mean the same plain number, and English carries it with the single word "four" every time.
What is worth noticing is not a second meaning but a pattern of use. Four often stands for completeness across the whole world, because the world was pictured as having four directions. So the Bible speaks of the four winds, the four corners (or quarters) of the earth, and four rivers flowing out of Eden to water the whole land. In Ezekiel's vision the living creatures each have four faces and move toward all four sides, a picture of God's reach in every direction. This is the ordinary number four doing ordinary counting; the sense of "the whole earth, all directions" comes from what is being counted, not from any special meaning hidden in the word itself.
Four also pairs naturally with other numbers in set phrases. "Three and four" is a way of saying "more than enough, again and again" (as in the refrain "for three transgressions and for four"), and "forty" (literally four tens) marks long, complete spans of time such as the forty years in the wilderness.