A lot depends on the native language of the person trying to learn English. English has many confusing constructions and word structures, and many words that are spelled the same but mean completely different things. For example, you play baseball with a 'bat', but you'd have a heck of a time hitting a pitched ball with that furry little winged mammal that lives in a cave. And a pitcher holds water, but also throws a ball. See what I mean? Many English words have their roots in other languages, from Spanish and French to Hindu. However, English is probably much easier to learn than Russian or Chinese, for example.