# Now
The word "now" marks a change in topic from garments for priests to consecrating priests. This chapter records the process of consecrating priests. The priests were to be set apart from the rest of Israel because Yahweh is holy.
# you must do
Here "you" refers to Moses.
# to set them apart
"to set apart Aaron and his sons"
# serve me
Here "me" refers to Yahweh.
# one young bull
a male cow