An example of the use of let's as a contraction is in the sentence, "Let's pray," which means "Let us pray."
Let's is always inclusive, which refers to both the speaker and the addressee, while let us is commonly exclusive, which refers only to the speaker.
- Let's go, we are late. - inclusive we
- Release us and let us go! - exclusive we
Negation of let's is let's not in standard English.
- Let's not talk about it.
Don't is also used, but it is often considered non-standard.
- Let's don't talk about it. (US)
- Don't let's talk about it. (UK)