The sacred months are specific blessed months

In these days, Muslims receive one of the sacred months, and they are glorified days, in which the reward is doubled and the consequence of wrongdoing is greater

The sacred months are specific blessed months in the Hijri calendar that were singled out by God and mentioned in His Holy Book:

إِنَّ عِدَّةَ ٱلشُّهُورِ عِندَ ٱللَّهِ ٱثْنَا عَشَرَ شَهْرًۭا فِى كِتَـٰبِ ٱللَّهِ يَوْمَ خَلَقَ ٱلسَّمَـٰوَٰتِ وَٱلْأَرْضَ مِنْهَآ أَرْبَعَةٌ حُرُمٌۭ ۚ ذَٰلِكَ ٱلدِّينُ ٱلْقَيِّمُ ۚ فَلَا تَظْلِمُوا۟ فِيهِنَّ أَنفُسَكُمْ ۚ وَقَـٰتِلُوا۟ ٱلْمُشْرِكِينَ كَآفَّةً كَمَا يُقَـٰتِلُونَكُمْ كَآفَّةًۭ ۚ وَٱعْلَمُوٓا۟ أَنَّ ٱللَّهَ مَعَ ٱلْمُتَّقِينَ

“Indeed, the number of months ordained by Allah is twelve—in Allah’s Record since the day He created the heavens and the earth—of which four are sacred. That is the Right Way. So do not wrong one another during these months. And together fight the polytheists as they fight against you together. And know that Allah is with those mindful (of Him).”

(Surah At-Tawbah, 9:36)

What is the virtue of the sacred months?

God favoured them over all other months of the year and honoured them over all other months. So, he singled out sin in them for veneration, just as He singled them out for honouring, and that is similar to the Almighty’s saying:

{حافظوا على الصلوات والصلاة الوسطى} (البقرة:238 ) {Preserve the prayers and the middle prayer} (Al-Baqara: 238).

The sacred months are called that because Islam forbade fighting between people during these months, and the Sunnah of the Prophet determined the sacred months to be four months

In a hadith recorded by Imam Al-Bukhari, the four months were mentioned by name. The Prophet SAW said:

“The division of time has turned to its original form which was current when Allah created the Heavens and the Earths. The year is of twelve months, out of which four months are sacred: Three are in subsequent Zulkaedah, Zulhijjah and Muharram, and (the fourth is) Rajab of (the tribe of) Mudar which comes between Jumadith-Thaniyah and Sha’ban.”

The virtue of the month of Dhul-Qa’dah

(1) It is the eleventh month in the Hijri calendar, and it is one of the sacred months in which God forbade injustice in her honour.
2) The month of Dhu’l-Qa’dah was given this name because the Arabs used to sit back from fighting during it, and it is the first of the sacred months successive
(3) The Qur’an mentioned the sanctity of the month of Dhu’l-Qa’dah in the words of the truth.

Here’s a list of what you can do in abundance during these four sacred months: 

Increase your worship.

Seek forgiveness.

Be conscious of your actions to ensure you don’t harm others.

Increase your Salawat upon the Prophet SAW.

Give  Sadaqah regularly.