Lets is the third-person singular form of the verb “let”, which means to allow or permit. It is used to indicate that one person is allowing or permitting something. For example:

• He lets his dog out every morning.
• She lets her kids stay up late on weekends.

Let’s is a contraction of “let us”. It is used to mean “let us” in a shorter, more informal way. It is used to encourage or invite someone to do something together. For example:

• Let’s go for a walk.
• Let’s order pizza for dinner.

In summary, lets is the third-person singular form of the verb “let”, which means to allow or permit, while let’s is a contraction of “let us” and is used to encourage or invite someone to do something together.