The phrase 'puellae cantant' translates to 'the girls sing' in English. This expression showcases subject-verb agreement, where 'puellae' is the subject in the nominative plural form meaning 'girls,' and 'cantant' is the verb in the present tense, third-person plural form meaning 'they sing.' Understanding how subjects and verbs agree in number is essential for constructing clear and grammatically correct sentences.