Hi Peter & welcome!
TXL and RXL probably speak for themselves they indicate a Transmitted or Received PilotAware traffic packet respectively
L! & L2 indicate whether an interface seems to be working correctly, and are actually replicates on the Home page, you will see a red/green indicator agains the ADS-B, Barometer, GPS Entries
if it flashes all green - all is OK, for any red flashes, you can check the Home page for the status
Thx
Lee