Chirality (Greek artificial word, handedness, derived from the root word χειρ, cheir - hand), also known as enantiomorphy in crystallography, refers to the property of certain objects or systems that their mirror image cannot be made to coincide with the original by rotation. Objects with this property are called chiral, as opposed to achiral.
Common examples are right and left hands or right- or left-handed snail shells. You can turn both hands so that the thumb points to the right. This means that the palm of the left hand points downwards and the palm of the right hand points upwards.
In organic chemistry, this is called a stereocenter. However, the term "chiral" is still commonly used in biochemistry. The terminology here is that a C atom can be a "chiral center", but "chiral" is then not the atom, but the molecule that contains the chiral center