Great question! As you might already know, the answer has to do with quantum mechanics and how subatomic particles (like electrons) behave. In fact, it turns out that at microscopic scales, subatomic particles exhibit behavior that makes them look like waves. If this sounds weird to you, you're not alone: it's one of the weirdest features of modern physics! Nevertheless, experiments tell us that this is how nature works.

So then the question of determining the precise location of an electron becomes that of determining the precise location of a wave. But by their nature, waves are always spread out! (If it helps, think of an ocean wave - you can usually say that the wave is "more or less" over there, but you can't pinpoint its location exactly because it has some spread). More importantly, it's not that we can't determine the precise location of a wave - it's that it doesn't even make sense to talk about a wave's precise location, because the wave is spread out. This is why you can't determine the exact location of an electron - an electron simply doesn't have an exact location, because it acts like a wave.