Suppose that I have 2 identical objects created by copy and paste. How do I move one and left the other stay at its position ? What are the hot-keys for this and clicking options in the Blender's workspace ?
In order to move an object with a key shortcut, press G to move the selected object(s). If you choose to cancel movement before you hit enter or click LMB, you can click RMB to cancel the movement. You can choose to move it just by moving the mouse, but you can also choose an axis by pressing x, y, or z after pressing "g".
If you want it to not move on a specific axis, then press Shift-(axis). For instance, if you don't want it to move up or down, press Shift-Z.
After pressing G, you can just move it a certain distance with your mouse. However, if you want to move it an exact distance, you can type in an amount after pressing G. You can also backspace, so you don't have to try al over again. Also, you press the - symbol to change the value you typed to a negative amount so it will travel backwards along the axis. The negative symbol switches the current amount's symbol, so if you hit - when the amount is set to a negative amount, it will change to a positive amount. Try this out to fully understand.
One more thing: It doesn't matter if you specify distance before choosing the axis you are moving on. You can even change amounts and change axis in-between each other, if that makes sense. The only important thing is that you press G before choosing distance or axis.
Please ask if any of this doesn't make sense.