前头 is a colloquial position word (方位词) meaning 'the front' or 'ahead'. It can be used spatially (e.g., 在...前头 'in front of...') or temporally (e.g., 排在前头 'rank ahead'). It is similar to 前面 but more informal and common in spoken Chinese. As a noun, it can follow a preposition; as an adverb, it modifies verbs of movement or position.