Unclear answer in Skydroid 16H User Manual

From the User manual section Q&A:

  1. Data transmission/telemetry cannot be connected
    Check whether the ground station is connected with UDP type to connect to the TX and whether
    the listening port is 14551. Check whether the baud rate is normal. Check if RX and TX is
    connected reversely (connect RX to TX TX to RX correctly)

Question:
1.) what is the significance of: " ground station is connected with UDP type to connect to the TX".
2.) what is the “normal” baud rate in expression : “Check whether the baud rate is normal.”
3.) what are RX and TX in expression : “Check if RX and TX is connected reversely (connect RX to TX TX to RX correctly)”
There are signals on serial Telemetry port, or Receiver, Transmitter devices ??

Can someone make me clear with answer 4.) from Q&A section of the manual.