This is a long day in terms of walking but there is no steep climb or descent so it will not be very demanding on the body.
You will pass through more hamlets today but the only one where you can find amenities is Castroverde before reaching the city of Lugo at the end of the day. In Castroverde you can also take some time to visit the ruins of a castle dating back to the 14th century and the gothic Iglesia de Santa María de Vilabade. After Castroverde you will find some vending machines on your way for refreshments.
The whole day one passes through rural areas before reaching Lugo. Lugo is the biggest city you will find on the Camino Primitivo before reaching Santiago. The entirety of the town is surrounded by Roman Walls and 71 towers. This whole structure is now a UNESCO World Heritage Site. The Cathedral of Santa María from 1129 is also worth visiting.