What does the English language has a deceptive air of simplicity means?

The phrase "the English language has a deceptive air of simplicity" suggests that while English may appear straightforward and easy to learn at first glance, it is actually quite complex and nuanced. This complexity arises from its irregular spelling, varied grammar rules, idiomatic expressions, and rich vocabulary. As learners delve deeper, they often encounter subtleties and exceptions that can make mastering the language challenging. Thus, the initial simplicity can be misleading.