HUP says that there are certain pairs of quantities and it is not possible to measure both beyond a certain degree of accuracy.
Position and momentum are perhaps the best known pair
So if you have an electron and you know exactly where it is you have no idea how fast it is moving
Conversely if you know it's momentum exactly you cannot say where it is.
The important thing to realise is that this is not down to experimental error or technology but rather a fundamental effect of the nature of reality.
No technology however advanced would be able to do this.
This is the basis for the old joke: Heisenberg is driving down the road when he is stopped by a policeman who says "Excuse me sir do you know how fast you were going?" "No" Says Heisenberg "But I know exactly where I am!"