He is six years old.

he Pronoun

— A person or animal that we do not know the gender of. Kill that spider, before he gets away!.

he Noun

— A he refers to a male person. — He is the name of the fifth letter of many Semitic alphabets such as Phoenician, Aramaic, Hebrew, Syriac, Arabic and others.

is Verb

— A form of the verb be when talking about someone or something else. He is late for class. Is it hot in here?

six Determiner

— (ordinal sixth) Six is the number that is after five and before seven. In numerals, it is 6. Most people sleep from six to nine hours a night.

six Noun

— The number 6. Three and three is six.

years

— noun (= old age, age, eld, geezerhood) a late time of life old age is not for sissies he's showing his years age hasn't slowed him down at all a beard white with eld on the brink of geezerhood — noun (= age) a prolonged period of time we've known each other for ages I haven't been there for years and years — noun (= days) the time during which someone's life continues the monarch's last days in his final years

old Adjective

— If someone or something is old, they are not young; they have been in existence for a long time. An old man has gray hair. — How old someone is, is their age. "Ashley, how old are you?" "I'm only 16 years old."