definition 1: to have a requirement for.
example: They need more money to support their families.
example: All animals need water to live.
example: The house needs painting and the windows need washing.
definition 2: to have or feel the necessity or obligation (to do something).
example: You need to sign the form on the front and back.
example: I need to leave now, or I’ll miss the bus.
example: I’m tired; I need to take a break.