Hello!
Lets and lets are based on the same verb,let, which means to allow or give permission.

Letsis a contraction of let us. You use it to make suggestions about what you and someone else should do.Lets go to the movies. Lets invite Mom.

Letsis the third-person singular present tense form of verblet, which means to allow or give permission.If Mom lets us go to the movies without her, Ill be surprised.

Hope you got it.
Regards!

Let’s with an apostrophe is a contraction of “let us,” which is used in all varieties of speech and writing to introduce a suggestion or request: Let us consider all the facts . Because “let us” often sounds overly formal, the contracted form, let’s occurs more frequently in colloquial speech and writing: Let’s go, Tigers! Let’s forget this ever happened.

Sometimes you’ll see redundancy with the use of let’s : Let’s you and me get out of here . This, of course, literally means, “Let us you and me get out of here.” If “you and me” is treated as an aside here, it can function to elaborate on the subject for emphasis and clarification. However, if not treated as an aside, the above example would be considered nonstandard English.