This section of the Bible, Numbers 6:23-27, is commonly referred to as the Priestly Blessing. Since Aaron was the first High Priest, it is also known as the Aaronic Blessing.
It is common for whomever is reciting the blessing to make their hands resemble the hebrew letter shin representing one of the hebrew words for God - Shaddai.
Other articles of interest include:
Image from Google images.
