Open the note and tap the share button. Your phone's share menu (Share note with...) opens: choose a messaging app, e-mail, or anything else.
What's shared: the note's text, its date and time, its phone number and e-mail if it has them, and a short line "Shared via 1krNote". Photos and videos are shared too where the chosen app supports them.
Only what you share leaves the phone, and only to the app you choose.
With an AI plan you can also ask the assistant: "Send this note to Anna by text"; it prepares the message for you to send (see "Sending a note by SMS or e-mail with the AI").