The term "relation" has several meanings, depending on its context.
1) In a general sense, relation refers to how two or more things are connected or related to each other. For example, in a family tree, the relations would be the connections between individuals such as parent-child, sibling, etc.
2) Relation can also refer to personal relationships between people, such as friendship, romantic partnership, and so on.
3) In mathematics, relation refers to a binary operation that relates elements of two sets. For example, an "equivalence relation" is a type of relation where every element in the first set has exactly one corresponding element in the second set (and vice versa).