فَيَبْتَدِئُ بِجَمْرَةِ الْعَقَبَةِ.
Translation: Then he begins with Jamrat al-Aqabah.
Jamrat al-Aqabah is the Jamarah toward Makkah among Mina's three stoning sites. On 10 Dhu al-Hijjah, the rite described here concerns this one Jamarah; stoning all three belongs to the following days.
The verb fa-yabtadiʾu signals sequence: the first rite after reaching Mina is this stoning. It is essential not to confuse the first day with the later days of tashriq.