In plain words
Our body, and the blood that moves in the body, everything, is the very gift of the mother and father. For their son's progress the mother and father bear many kinds of toil, bear hardships, go hungry even themselves, and bring up their children: they are the greatly holy ones. With the feeling called putreṣaṇa, hoping that their sons should never in the future fall prey to any hardships, sorrows or worries, the mother and father gather many kinds of goods and vehicles and hand them on, and hope that their sons will live out their future happily. To honour such revered parents and make them glad, to serve them, all their lifetime to carry out their command as on one's head, and when such parents have passed away, to do good deeds in their memory and give in charity, to make an offering to them for their pleasure every year, or else once a month, to keep these as the days called taddinam, to remember them with Prema and shed tears from both eyes: this is the true Pitṛ-yajña.
Manuṣya-yajña. When a fellow man, one who is our fellow human being, falls prey in many ways to hardships and sorrows, to take that occasion and give him with our own hands all the help he needs, to give fitting charity so as to free the poor from their sorrows and give the sick the right care, to enter society, take part in the service of society and follow the service of our fellow men, to make them happy and be happy oneself: this is Manuṣya-yajña. More than this: to welcome the guest who comes to the house and the stranger, to recognise the equality that says my neighbour is my fellow man, to recognise that all human beings belong to one race, to feel the sameness that says his hardships are like my hardships and his joy like my joy, and to take part in the service of others: this is Manuṣya-yajña.
Bhūta-yajña. Usually every man in his house, cattle or a dog, some other animal, birds or young ones, such creatures as these, we bring them up. To show true affection to these creatures, to satisfy those creatures at the right time, to give them food at the right time, to grow this kind of Prema towards all creatures, to believe that God is Himself the form of all creatures, and to make the effort it takes to care for and nourish such dumb cattle, birds and beasts. In olden times women would sprinkle cow-dung water in front of the house every day, clean it, and have rangoli drawn beautifully for the house. Now, with what material did they draw these rangoli? They would put rice flour under the rangoli so that it would be beautiful and ornamental, and held that this brought welfare to the home; in this very thing lies kindness to creatures.