What does Siya mean?
A regional and poetic short form of सीता (Sītā), the heroine of the Ramayana, whose name means 'furrow' (she was found in a ploughed field). Siya is widely used in Hindi devotional usage (as in 'Siya-Ram').
What does Reva mean?
From Sanskrit reva (रेवा), an ancient name of the sacred Narmada river, connoting flowing water. Well established.