Nivea is a Latin word for a colour. The brand's maker, Beiersdorf, says the name comes from nix, nivis, "snow," and means "snow white." It was picked because the cream inside the tin was white.
The adjective behind it is niveus, "snowy." Etymonline traces it to the stem of nix and, further back, to a Proto-Indo-European root for snow. That root also produced the English word snow, the German Schnee and the Dutch sneeuw. So a German skin cream carries a Latin cousin of an ordinary English word.
The company began as a Hamburg laboratory. Paul Beiersdorf founded his firm on 28 March 1882, and the pharmacist Oscar Troplowitz took it over in 1890. Troplowitz worked with the dermatologist Paul Gerson Unna, who pointed him to an emulsifier called Eucerit.
Eucerit was the real invention. Wikipedia credits it to the chemist Isaac Lifschütz, patented in 1900. It is made from lanolin, a fat from sheep's wool. Beiersdorf glosses the name Eucerit as ancient Greek for "beautiful wax." It let oil and water stay mixed instead of separating.
The Nivea name was already in use before the famous cream. Wikipedia records a Nivea soap in 1906. In 1911 Beiersdorf launched Nivea Creme, which Wikipedia calls the first stable water-in-oil emulsion. Beiersdorf lists its other ingredients as glycerin, a little citric acid, and rose and lily-of-the-valley oils.
The first tin did not look like the one people know now. It had an ornate Art Nouveau design. In 1925 the company switched to a plain blue tin with white lettering, and that look has stuck.
The name had a rough twentieth century. During the Second World War the Nivea trademark was expropriated in many countries, and Beiersdorf later had to win those rights back. The word it fought for was never really its own invention. It was a Latin adjective that any Roman could have read on the lid.