Ok, this part is slightly complicated and cannot be explained in a few words.
This will make explaining easier.
"甲子旬中空戌亥" would mean:
if one is born in the Year of Jia Zi 甲子, Xun Kong 旬空 will be charted in the Xu 戌 Palace.
Why Xu 戌 Palace and not Hai 亥 Palace?
This is because, the stems and branches are paired either Yang-Yang or Yin-Yin (60-year Cycle).
And since Jia Zi is Yang-Yang, Xun Kong will be established in a Yang-branch Palace,
which in this case, is Xu Palace.
In the following year, Yi Chou 乙丑, which is a Yin-Yin, Xun Kong will be established in Hai 亥 Palace.
Followed by Year of Bing Yin 丙寅 (Yang) of which Xun Kong is established in Xu 戌 Palace again.
Example:
Birth Year being Jia Yin 甲寅, Xun Kong 旬空 would be at Zi 子 or Chou 丑 Palace.
Jia Yin being Yang, Xun Kong is established at Zi Palace (Yang).
If you are still unsure, you may check the table here.
