"S1, S2, ..., Sn" represents a sequence of elements, where each element is denoted by "S" followed by a number. This notation is commonly used in mathematics and computer science to describe ordered lists or series. The "n" indicates the total number of elements in the sequence, which can be finite or infinite. In programming, sequences like "S1, S2, ..., Sn" can represent arrays or lists, where each "Si" is an individual item. These sequences are useful for organizing data, performing calculations, or iterating through elements in algorithms, making them fundamental in fields such as data analysis and software development.