Specifically, the exact momentum (energy) and the exact position can't be known simultaneously. Because something in motion will tend to remain in motion, you can determine the direction by knowing the momentum. (For example, if a car has forward momentum, you know it's moving in the forward direction.) So, you can calculate the direction of an electron, and you can measure it, just not with infinite accuracy.

You are asking a question that is related to Heisenberg's Uncertainty Principle. This principle states that, if you know one thing about an electron, you can't know another thing. So, you can know the position of an electron, but then you can't know its momentum - how fast it is going and how heavy it is. Or, you can know the momentum, but then you can't know the position. I think this is a principle of real experiments. I'm reading about it in Wikipedia, here:

You can think about it like this: If you're using a method to measure Exactly where the electron is, the measurement is interacting with the electron in some way, and so you can't know the exact momentum of the electron. Or, if you're using a method that measures the momentum exactly, that measurement is interacting with the electron in some way, so you can't know exactly where the electron was when you measured its momentum.

The wikipedia article gets complicated quite quickly, so you might want to look for other information on the subject.

Keep asking questions!
Best wishes,

There is something called the Heisenberg Uncertainty Principle that limits what you can know about the mass, position, energy, and time of any particle, no matter what it is. It's possible to know exactly where an electron is at any given moment, but you will have no idea of where it's going or how fast - or you know precisely what direction it's moving in, but have no idea where it is. This is due to a fundamental property of physics at small scales that is difficult to describe in layman's terms: particles inhabit a wave-like probability distribution of energy and position states, and observing something alters it, so that you don't know where it will be after you observe it.