Is it correct to say 'Io ho 25 anni' or 'Io sono 25 anni' in Italian?

Io ho 25 anni, not Io sono 25 anni, is correct in Italian. Italian opts to conjugate the verb avere ("to have"), not essere ("to be"), when a person's age is at stake. The correct phrase -- which need not begin with the personal pronoun io ("I"), other than for emphasis, since context and the verb endings identify the subject as the first person singular -- translates literally as "I have 25 years" and will be pronounced "EE-o VEN-ti-TCHEEN-kwey AN-nee" in Italian.