$N = n\,N_A$ — capital-N equals n times N-A — turns a headcount in moles into actual things: multiply by $6.02 \times 10^{23}$. Read the subscript aloud as “N sub A”; the A is for Avogadro, who never measured it and has it named after him anyway, which is science being generous.

Try to feel the size, because the exponent is the entire lesson. A mole of grains of sand would bury Canada kilometres deep. A mole of seconds is about ten thousand times the age of the universe. If you counted molecules at one per second you would need $2 \times 10^{16}$ years to finish a teaspoon of water. So when a magnitude stage asks for the power of ten, answer it before you touch a key: a couple of moles is always somewhere around $10^{24}$, and any answer that comes back as a normal-looking number has been divided when it should have been multiplied.