Which one is the right?

As a slogan on a poster I would prefer "SUCCESS: it is how hard work is named", or "SUCCESS: that is how hard work is named"

As a sentence in an essay I would prefer: "Success is how hard work is named."

In Spanish, as you know, often "it" is not expressed, and in general Spanish is a "pro-drop" language, but English is decidedly less so. Re-using the pronoun in the first example to stand again for the antecedent "success" makes it more emphatic. In the second instance, we are only defining the word "success" as you see it.

So... the short answer is that it depends on context, and these two examples are not really clear cut. However, discounting exceptional cases, English does not usually drop the subject of a sentence. So if you require a neuter pronoun, use "it" in place of a known antecedent. "I have a car." "It is red." We cannot use only "Is red." for the second sentence.