"Ampere" means 1 coulomb of charge every second.
12A means 12 coulombs of charge every second.
5.2 minutes = (5.2) x (60 seconds) = 312 seconds
12A for 312 seconds means (12) x (312) = 3,744 coulombs of charge
1 coulomb is the amount of charge carried by 6.24 x 10¹⁸ electrons .
So 12A for 312 seconds means (3,744) x (6.24 x 10¹⁸) electrons.
That's 2.336 x 10²² electrons .
or 23,360,000,000,000,000,000,000 electrons .
(rounded to the nearest 10 quintillion).