From The Heroes of Might and Magic III wiki

Signs are Adventure map objects that contains a short piece of text. While they don't confer any bonuses, reading them might still be a good idea as they can contain helpful hints.

Technical Information

Maximum length of text - 150 characters.

Default random messages:

• Beyond here be Dragons
• Danger
• Do Not Enter
• Keep Out
• Members Only
• No Admittance
• No trespassing
• Proceed at Your Own Risk