All praise be to Allah.
In Islamic terminology, the zawal time is the exact time when the sun is at its absolute zenith or meridian at mid-day i.e. noontime.
How many times and when does it occur in a day?
Once a day everyday at mid-day, the sun reaches its zenith or its meridian.
Is it true that no Namaaz should be offered during this time?
Amr ibn 'Abbas related that he said, "O Prophet of Allah (saws), inform me about the prayer (times)." He said, "Pray the morning (fajr) prayer, and then abstain from prayer until sunrise and the sun has completely risen, for it rises between the horns of Shaitaan. That is when the unbelievers prostrate to it. Then pray (nawafil), as your prayer will be witnessed and attended to until the shadow of a spear becomes less than its length. At that time stop praying, for at that time (zawaal) the Hell-Fire is fed with fuel.When the shade comes, you may pray (dhuhr), for your prayer will be witnessed and attended (to by Angels) until you pray the afternoon (Asr) prayer. Then abstain from praying until the sun sets, for its sets between the horns of Shaitaan, and that is when the unbelievers make prostrations to it." (Related by Ahmad and Muslim.)
It is hence proven in saheeh Hadith that the Messenger of Allah forbade the believers from offering any salah
1. during the sun rise or till it has risen completely above the horizon.
2. When the sun is at or near its meridian(zawaal).
3. and after the afternoon (Asr) prayer until the sun has completely set.
these times are the times when the sun is risen or set in between the horns of Shaytaan and when the hellfire is fueled. May Allah protect us.
If we offer Fajr prayer after the complete sunrise will it be QAZA
Allah tala has commanded his slaves that they must offer prayer on time and the appointed time of the fajr prayer is before sunrise. Hence after sunrise, the fajr prayer will be considered as Qaza.
Allah says in the Holy Quran Chapter 4 Surah Nisaa verse 103:
Indeed the Salaat is a prescribed duty that should be performed by the believers at (their) appointed times.
To miss or neglect or delay the prayer beyond their appointed time is not even an option in Islam except with a valid and genuine reason. Doing that is a grave sin and reprehensible in front of Allah tala.
Allah Says in the Holy Quran Chapter 107 Surah Al-Maun verses 4-5:
So woe to the worshippers. Who are neglectful of their prayers
Whoever sleeps through or has forgotten to pray a certain prayer should pray it when he wakes up or remembers the prayer. Abu Qatadah related that sleeping through the prayer time was mentioned to the Prophet (saws) and he (saws) said, "There is no negligence in sleep, but negligence occurs while one is awake. If one of you forgets a prayer or sleeps through its time, then he should pray it when he remembers it."
Related by an-Nasa'i and at-Tirmidhi.
Anas related that the Prophet (saws) said, "Whoever forgets a prayer should pray it when he remembers it, and there is no expiation for it save that."
Related by al-Bukhari and Muslim.
What about the zuhar prayers if offered after the ASAR adan?
Jarir ibn Abdullah narrated that the Angel Jibrael (a.s.) came to the Messenger of Allah (saws) and said to him, "Stand and pray," and they prayed the noon (dhuhr) prayer when the sun had just passed its meridian. He then came to him (saws) for the afternoon (asr) prayer and said, "Stand and pray," and they prayed the afternoon (asr) prayer while the length of a shadow of something was similar to the length of the object. Then he came at sunset and said, "Stand and pray," and they prayed the sunset (magrib) prayer when the sun had just disappeared. Then he came at night and said, "Stand and pray" and they prayed the night (isha) prayer when the twilight had disappeared. He came again when dawn broke (and they prayed the morning (fajr) prayer). Then Jibrael (a.s.) came on the next day at noon and said (to the Messenger of Allah (saws)), "Stand and pray," and they prayed the noon (dhuhr) prayer when the length of the shadow of something was close to the length of the object. Then he came for the afternoon prayer and said, "Stand and pray," and they prayed the afternoon (asr) prayer when the shadow of something was twice as long as the length of the object. Then he came at the same time (as the previous day) for the sunset (magrib) prayer, without any change. Then he came for the night (isha) prayer after half (or a third) of the night had passed. Then he came when the sky was very yellow and said, "Stand and pray," and they prayed the morning (fajr) prayer. Then Jibrael (a.s.) said, "Between these times are the times for the prayers.
Related by Bukhari, Ahmad, an-Nasa'i and at-Tirmidhi.
In light of the above guidance, if one prays the prescribed prayer between the two specified periods, their prayer will be considered on-time; and it was the preferred Sunnah of the Messenger of Allah (saws) to offer the prescribed obligatory prayers at its earliest times.
If the azan for the asr prayer has been said then the time for zuhur prayer is over and it has become qaza or will be considered delayed.
And Allah knows best and He is the source of strength.