# According to the customary way of choosing which priest would ... burn incense
This sentence gives us information about priestly duties. (See: [[rc://en/ta/man/translate/writing-background]])
# the customary way
"the traditional method" or "the usual way"
# chosen by lot
A lot was a marked stone that was thrown or rolled on the ground in order to decide something. The priests believed that God guided the lot to show them which priest he wanted them to choose.
# to burn incense
The priests were to burn sweet-smelling incense as an offering to God each morning and evening on a special altar inside the temple.