If someone reminds you of a fact or event that you already know about, they say something which makes you think about it.

You use remind in expressions such as Let me remind you that and May I remind you that to introduce a piece of information that you want to emphasize. It may be something that the hearer already knows about or a new piece of information. Sometimes these expressions can sound unfriendly.

If someone reminds you to do a particular thing, they say something which makes you remember to do it.

If you say that someone or something reminds you of another person or thing, you mean that they are similar to the other person or thing and that they make you think about them.