The term "the latter" refers to the second of two things that have previously been mentioned. It is often used in contrast to "the former," which indicates the first of the two mentioned items. For example, if you say, "I like apples and oranges; the latter is more refreshing," you are indicating that oranges are the second item and are the focus of the statement.
The phrase "the latter" comes from the Old English word "lætra," meaning "later" or "the second mentioned." It has roots in the Proto-Germanic *laitra, which translates to "later" and is related to the word "late."