12 This calls for patient endurance on the part of the people of God who keep his commands and remain faithful to Jesus.

Read Revelation 14:12 Using Other Translations

Here is the patience of the saints: here are they that keep the commandments of God, and the faith of Jesus.
Here is a call for the endurance of the saints, those who keep the commandments of God and their faith in Jesus.
This means that God’s holy people must endure persecution patiently, obeying his commands and maintaining their faith in Jesus.