The FPS/Network Display box shows you three values:
FPS (graphical frame rate in Frames Per Second, or FPS)
L*(Latency, or data transmission delay between your system and the iRacing server)
Q (Quality of the connection to the iRacing server)
S (Sevice, shownig the state of Synchronization between your computer and iRacing)
The "FPS" indication at the top of the display is a numerical value that represents your frame rate in Frames Per Second (FPS), which is a reflection of your graphical performance.
The "L" portion is a bargraph that represents your latency*of your connection, or the time delay for data transmitted between your PC and the iRacing servers.* This bar can vary in length and in color -- a shorter bar length or a green bar indicates a low latency or delay, and if this bar turns red that indicates that your latency is reaching an unacceptable acceptable level.* When you see a red bar here, this is an indication that the latency has dropped to an acceptable level, which may result in a disconnection from the iRacing server.
The "Q" portion is a bargraph that represents your connection quality, and this bar can display varying colors -- a green bar is good, yellow or orange means less than ideal connection quality, and it will turn red if your quality is dropping below an acceptable level.* When you see a red bar here, this is an indication that your connection may drop and you may be disconnected from the iRacing server.
The "S" portion shows the service/sychronization state, or the "skew" of your connection to the iRacing servers.* As with the "Q" bar, a green bar is good, yellow or orange means less than ideal synchronization with the iRacing service, and it will turn red if your synchronization is dropping below an acceptable level.* When you see a red bar here, this is an indication that your connection may drop and you may be disconnected from the iRacing server.