The phrase "a certain" indicates that Luke is introducing a new person in the story. (See: [[rc://en/ta/man/translate/writing-participants]])
# an Alexandrian by birth
"a man who was born in the city of Alexandria." This was a city in Egypt on the north coast of Africa. (See: [[rc://en/ta/man/translate/translate-names]])
"he knew the scriptures thoroughly." He understood the Old Testament writings well.
# Apollos had been instructed in the teachings of the Lord
This can be stated in active form. AT: "Other believers had taught Apollos how the Lord Jesus wanted people to live" (See: [[rc://en/ta/man/translate/figs-activepassive]])
# Being fervent in spirit
Here "spirit" refers to the entire person of Apollos. AT: "Being very enthusiastic" (See: [[rc://en/ta/man/translate/figs-synecdoche]])
# the baptism of John
"The baptism that John performed." This is comparing John's baptism which was with water to Jesus' baptism which is with the Holy Spirit.
# the way of God
How God wants people to live is spoken of as if it were a road that a person travels. (See: [[rc://en/ta/man/translate/figs-metaphor]])