"My father is coming home."
Translation:मेरे पिता घर आ रहे हैं ।
Pluralising the noun serves as an honorific. Since we would normally want to convey respect while addressing or mentioning our father, we say 'मेरे पिता' and not 'मेरा पिता'. You can also add 'जी', which is an another honorific (मेरे पिता जी).
Another example, My teacher is good - मेरे गुरु जी अच्छे हैं।