On Snapchat, the **S** would typically be written beside the name of a friend in your chat or friend list. It abbreviates as Snapstreak i.e. you and that friend have shared snaps with each other every day. The figure beside it indicates the length of days of the streak.
The S generally comes before the name of a friend or Snap, and denotes a Snapchat Score. It provides the summation of all activity on the application, such as snaps sent and received, stories posted, and any other interaction, and it provides an estimate of how much a user engages with the application.
