"Mille" is Latin for thousand. A CPM of two dollars means one thousand views cost two dollars, so fifty thousand views would cost one hundred dollars. That arithmetic is all the term encodes.
CPM is useful because it normalises spend across channels of wildly different sizes. It says nothing, however, about the quality of those views — a thousand views from an audience that cares is not equivalent to a thousand from an audience that does not.
In clip marketing, a rate expressed per thousand views is what connects a program's budget to the clips it funds. Different programs set different rates.