A more thorough explanation:

A descriptive word is a term that describes a general characteristic or function of a product or service. For example, "soft" is a descriptive word for a pillow, and "fast" is a descriptive word for a car.

However, a descriptive word cannot be registered as a trademark unless it has acquired secondary meaning in the minds of consumers, meaning that it is directly associated with one brand. This is because a trader cannot appropriate words or symbols that are public property and that others may use with equal truth and right for the same purpose.

For instance, "Apple" is a descriptive word for a fruit, but it has acquired secondary meaning as a trademark for the technology company. Similarly, "Kleenex" is a descriptive word for facial tissue, but it has become synonymous with the brand name.

These examples illustrate how a descriptive word can become a trademark if it has acquired secondary meaning in the minds of consumers, allowing it to be associated with a specific brand.