Can you explain this ruling in more detail, “A person who observes a Qadha for the fast of Ramadhan can break his fast before Zuhr”. Does this mean if I keep a Qadha fast, I can open my fast before Zuhr and it will still count?
Bismihi ta'ala
If you are doing qadha' for shahr Ramadhan fasting, you are allowed to terminate your fasting and break-off from it, anytime in the morning, until zawal, or salat dhuhr time.
You are not allowed to break your qadha' fasting anytime after dhuhr. If you do, there is a kaffarah.
This is different to Mustahab fast, where you can break your mustahab fast anytime, before dhuhr, or after dhuhr.
And Allah knows best