There is obviously a difference between “A bear eats shoots and leaves.” and “A bear eats, shoots, and leaves.”

There is also a difference between “I like to watch the sunset”.  or  “I like to watch the sunset.” Both are correct, but obviously, to express yourself correctly in English, you need to know which one to use.

Finally, there is an obvious mistake here: "I love to eat spanish food." Can you spot the mistake?* 

The correct use of punctuation marks is an essential tool in writing well in English, as essential as good vocabulary, good grammar, and good spelling. Without it, your writing can just seem like a list of words. Thus, knowing the basic rules of punctuation is fundamental, not only to being able to write well in English, but also to convey what you really want to say in a clear and concise way. We all want to be understood, and not misunderstood (especially when talking about our grandmothers)! The NESE On-Line Punctuation Course is a key step in ensuring that your written English is both easily understood and effective.

*In English, the names of countries, and the adjectives derived from their names, are always capitalized. (Look how many commas were used here!)