What does 'Refer to the owner's manual for coolant refill' mean?

[AugustLee]

Directly add coolant or distilled water to the specified level, or visit the nearest 4S shop for maintenance. The following is an introduction to vehicle coolant: 1. Introduction to coolant: The full name is antifreeze coolant, meaning it has antifreeze functionality. Antifreeze prevents the coolant from freezing and expanding during cold seasons when the vehicle is parked, which could crack the radiator and damage the engine cylinder block. Its main function is to maintain the engine within the normal temperature range, while also providing antifreeze, anti-boiling, and anti-corrosion effects. 2. Coolant location: On the expansion tank in the engine compartment, there are markings indicating the upper and lower limits of the coolant level. Visually observe the coolant level; if it is between the upper and lower limits, it is at a normal level. If the coolant level is found to be too low, it needs to be refilled as soon as possible. When refilling, ensure the coolant level is between the upper and lower limits of the expansion tank.