What does it mean to send a health code within 24 hours?

It means to give you your health code color within 24 hours.

During the period of closed management, the relevant places will not issue red, yellow and green health codes for the time being.

Health codes are based on real data and can be generated by citizens or people who have returned to work through online declaration and background audit. As an individual entering and leaving electronic certificate locally, the QR code can be declared once, which is universal in the whole city.