He measured the court - This was the court of the priests. See FFF in the plan.
Albert Barnes
Notes on the Whole Bible
The court - The inner court (B) where was the brass altar Ezekiel 43:13.
The new chapter would begin better at Ezekiel 40:48.
SDA Bible Commentary (limited)
Volume 1-7
47. He measured the court. This was the court of the altar (p. 716, R), a square of 100 cu. (about 170 ft.; 51.8 m.), in the center of the inner court.