In one sentence: Excel seems magic because when you copy and paste cells the references change to still work, but you can understand in less than a minute exact

In one sentence: Excel seems magic because when you copy and paste cells the references change to still work, but you can understand in less than a minute exactly how and why that happens if you learn R1C1. In two more sentences: Specifically if you're in cell A1 and you enter =B1 what is actually stored is =RC[1] (same row, one column more relative to this cell). So if you copy that into cell H50 it will still be RC[1] and now evaluate to I50.