Don't confuse
实足 ('the full / exact amount') with
十足 — same pinyin, different characters, meaning 'one hundred percent, fully'.
实足三十岁 = 'a full thirty years old (exactly that age)';
信心十足 = 'full of confidence'.
实足岁 specifically means age counted in completed years (Western reckoning), as opposed to
虚岁, the traditional 'nominal age' that counts the year of birth as one.
