Apostles are missionary evangelists sent by God. They travel to share the good news about Jesus with others.
Here, the prophets seem to be from the New Testament, not the Old Testament (see 3:5; 4:11; see also 1 Corinthians 12:10, 28–29; 14:1–5, 22–24, 29–32, 39; compare Acts 13:1; 19:6; 21:9–10). In both the Old and New Testaments, prophets do not primarily predict the future. Instead, they are empowered to speak a message from God (see 1 Corinthians 12:10).
on the foundation of the apostles and prophets: This means the church is based on their faithful witness to the saving message of Christ (see Revelation 21:14; compare Matthew 16:18). However, Christ Jesus himself is the cornerstone, the Messiah, Savior, and Lord (compare 1 Corinthians 3:11). The cornerstone is the most important stone in a building’s foundation (see Isaiah 28:16; Mark 12:10; Acts 4:11; 1 Peter 2:6–7).