To say means to speak words aloud or express something through language. When you say “good morning” to your teacher, you're using your voice to communicate a greeting. When a character in a book says something brave, the author is showing us the character's words.

Says is the present tense form used with he, she, or it. “She says she's ready for the spelling bee.” “The sign says to keep off the grass.” Notice that written words can say things too: a text message, a poster, or even a facial expression can say something without making any sound at all.

The word often appears in reported speech, when you're telling someone what another person expressed: “My friend says it's going to rain tomorrow” or “The recipe says to preheat the oven.” You might also use says when describing what something means or indicates: “The thermometer says it's 85 degrees outside.”

People sometimes use the phrase “goes without saying” to describe something so obvious it doesn't need to be mentioned, even though the speaker just mentioned it anyway.