Recall that ions are atoms or molecules that have gained or lost electrons, resulting in a net electrical charge.
Understand that when an atom loses one or more electrons, it has more protons than electrons, giving it a positive charge; this positively charged ion is called a cation.
Conversely, when an atom gains electrons, it has more electrons than protons, resulting in a negative charge; this negatively charged ion is called an anion.
A neutral atom has an equal number of protons and electrons, so it has no net charge and is not considered an ion.
Therefore, the best description of a cation is 'an ion with a positive charge.'