The semi-ironic statement refers to the persuasive power of numbers, and succinctly describes how statistics, even accurate ones, can be used to bolster an inaccurate argument through such methods as selectively choosing data, ignoring bad results and over-emphasizing good results.
There is some doubt as to whether the statement was actually coined by Disraeli. There is no evidence for Disraeli saying or writing the phrase other than mention in Twain's autobiography. Alternative attributions include the radical journalist and politician Henry Labouchère (1831-1912).
This topic has received many popular expositions, notably the 1954 book How to Lie with Statistics by Darrell Huff, which is still in print a half-century after it was written.