The word "next" refers to something that comes immediately after something else in a sequence or order. It can indicate the following item in a list, the coming event in time, or something that is close in position. For example, if you are talking about days of the week, after Monday comes Tuesday, so you can say that Tuesday is the "next" day after Monday.
The word "next" originated from Old English "nēxt," which is a superlative form of "near." Its roots are connected to Proto-Germanic and Proto-Indo-European languages.