"Apple is sweet."

Translation: सेब मीठा होता है।

[JGvXPd]

You need a definite article in this sentence. "The apple is sweet." Or, if you're making a general statement about apples in general—"Apples are sweet"—then the Hindi should be, "सेब मीठे होते हैं।"

[CCanton675]

The English sentence could be "The apple is sweet" or "An apple is sweet" but "Apple is sweet" is ungrammatical in English