Telemetry is the process of collecting data showing how the robot is functioning and making that data available to be analyzed either during or after operation. Telemetry includes:

• Publishing Robot Data - sending out data on the network so it can be viewed on the Driver Station
• Dashboards - software tools to display published robot data while tunning
• Data Logging - saving data to flash memory in the RoboRio so it can be viewed later
• Data Log Viewers - software tools to pull data out of a log file and display it

References:
WPILIB Telemetry: Recording and Sending Real-Time Data
https://docs.wpilib.org/en/stable/docs/software/telemetry/telemetry.html