A more thorough explanation:

Definition: Sex refers to the biological differences between males and females, including their physical and reproductive characteristics.

Sex can also refer to sexual intercourse or sexual relations between individuals.

Examples:

• Male and female humans have different reproductive organs, hormones, and physical characteristics such as body hair and muscle mass.
• John and Jane had sex last night.
• Consent is important in all sexual relations.

The first example illustrates the biological aspect of sex, while the second and third examples refer to sexual activity between individuals.