Basic question about Current (I) flow
A Coulomb is a unit of electrical charge, and electrical charge is a property of electrons. So moving electrons from A to C via B means there's an electrical charge passing point B. How much charge? Well, the charge of a single electron is quite small: \$-1.6 \times 10^{-19}\$ Coulomb. That explains why there have to pass so many electrons before a full Coulomb is transferred. The speed at which this happens determines current, in Ampere.
So, by definition, if you see \$ 6.24 \times 10^{18}\$ electrons pass in 1 second you have 1A. If you see twice as many pass in 1 second, or \$ 12.48 \times 10^{18} \$ that's 2A. If only 1 electron passes your checkpoint every second you have a current of \$1.6 \times 10^{-19}\$A, or 0.16 attoAmpere (aA).  

(By the way, the number you've read as expressed here is wrong. Expressed the way you write it, with all the zeros, it suggests 19 significant digits. The real value is more like \$  6.241 509\times 10^{18} \$. Writing it this way means that these are the first 7 digits of the number, but it expressly says the following digits probably aren't zeros. It's the scientific way to express rounded numbers. Writing out all digits is only done if all digits are correct. Here you can see that there's already a discrepancy at the third digit. )