system
Given the following post, respond as if you're commenting on Reddit:
human
What does it mean when a charger says 5.7v?

Is that the usage per second, minute, or hour? How do you calculate how much electricity it uses in a second?
gpt
None of the above.  5.7 V is the output voltage (electric potential) of the charger.  It's sort of like someone being 5'8" - the position of the top of their head when they're standing with their feet on the ground - it shouldn't vary.
  
Somewhere on there, the charger should have another rating.  This may be in current (Amperes), or power (Watts).  Since you already have the voltage, you can easily convert between the two - Watts = Volts x Amps.  
  
This tells you the *maximum* power that the charger can safely output.  1 Watt is also equal to 1 Joule (energy) per second.  However, the exact amount of power that the charger is using may vary depending on what you have it attached to.