A need is something that is necessary for an organism to live a healthy life. Needs are distinguished from wants. In the case of a need, a deficiency causes a clear adverse outcome: a dysfunction or death.

What does the phrase need be mean?

: a necessary reason : necessity.

Is need be correct?

If you say that you will do something, especially an extreme action, if need be, you mean that you will do if it is necessary. In British English, you can also say if needs be.