The phrase 'pueri veniebant ad scholam' translates to 'the boys were coming to school' in English. This term illustrates the use of the fourth conjugation in Latin, which is characterized by verbs that have a present stem ending in '-i' and a specific set of endings for each tense. In this phrase, the verb 'veniebant' is the imperfect tense form of 'venire,' highlighting an ongoing action in the past, while 'pueri' and 'ad scholam' provide context about who is performing the action and where they are going.