The closest translation I can think of for Tension is mood, feelings.
Tension UP means: To be excited about, to get motivated, to energize, to be happy.
Basically anything that increases your “Tension” or state of mind, body and soul.
Tension Down obviously means the opposite.
People will also use the word Tension alone.
Sort of like,
Your tension is a bit low today?
This job really lowers my tension.
Looking at that chick really raises my tension.
That dude’s tension is a bit too high…what a loser.
how’s your tension today?