To be

[Jignesh]

I just read on Facebook the following quote:
There is a time to be a nice person and there is a time to say enough is enough.
Why we need " to be" in the sentence? What type of sentence is this and what is the grammatical role of to be in the sentence?

[Alan]

It is an adjectival infinitive modifying the noun 'time', and meaning essentially 'at which it is necessary/appropriate to be...'