This song is an artistic interpretation of the traditional blessing that a Jewish father gives his children on the eve of the Sabbath. This blessing has two parts, and is different for a son or a daughter.
For a son:
May G-d make you like Ephraim and Menasheh.
Yesimcha Hashem ke-Efrayim vechi-Menasheh
For a daughter:
May G-d make you like Sarah, Rebecca, Rachel, and Leah.
Yesimeich Hashem ke-Sarah, Rivkah, Racheil ve-Lei'ah.
Second part, for both:
May G-d bless you and watch over you.
May G-d shine His face toward you and show you favor.
May G-d turn His face toward you and may He grant you peace.
Yevarechecha Hashem ve-yishmerecha.
Ya'eir Hashem panav eilecha viy-chuneka.
Yisa Hashem panav eilecha ve-yaseim lecha shalom.
The second part of the blessing is also known as the Aaronic blessing, and is the blessing that the priests, or kohanim, use to bless the people of Israel.
While saying this blessing, the father places his hands on the head of the child being blessed.