A symbol doesn’t depend on text, so it can be recognized in any language, and that can help extend your brand’s reach.
If you’re thinking about mobile marketing and about designing an app for your business, a visual symbol will translate easily into an icon on a touchscreen device.
Certain icons and symbols vary in meaning across cultures (for example, some people see owls as signs of wisdom, while others associate owls with death, and you really don’t want to mix those ideas in a logo).
Your logo is your brand, and having a brand symbol that translates well across multiple mediums is an important part of sharing what your company has to say.