Question

what is high tension in wire?

Answer 1

means a high voltage pull due to ressistance

Answer 2

High tension leads or high tensioncables or spark plug wires or spark plug cables are the wires that connect a distributor, ignition coil, or magneto to each of the spark plugs in some types of internal combustion engine. ...High tension leads, like many engine components, wear out over time.
pic with high tension lead....

happy New year ......