Lag: It is the delay in the connection between one computer and another. In the case of games, the delay occurs in the communication from a computer to a server.
Ping: Latency rate, the higher the ping, greater delay you will have to send the data to a server and get the information back.
FPS: Frames per second means the amount of frames played at the time of the game. The more FPS, the better your game display.
TCP: Connection protocol that provides reliable communication with various features..
UDP: Real-time connectionless transport protocol, which provides faster communication but low reliability."