(The All Compelling)
The One that nothing happens in His Dominion except that which He willed.
Al-Jabbar (in arabic: ٱلْجَبَّارُ) means the highest, whatever he decrees will come to pass without fail. He restores all of creation. He heals the broken hearted, binds their wounds, brings comfort to the weak. He compels each and everything to his divine will but is never Himself compelled.
From the root j-b-r which has the following classical Arabic connotations: to restore something to sound, right or good state to bring back to normal, reform to benefit, to confer a benefit to be supreme, high, above all of creation to be compelling, irresistible.
As a name of Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ al-Jabbar is only mentioned once in the Qur'an.
"He is Allah, other than whom there is no deity, the Sovereign, the Pure, the Perfection, the Bestower of Faith, the Overseer, the Exalted in Might, the Compeller, the Superior. Exalted is Allah above whatever they associate with Him." (59:23)
There are many other verses which we can refer to which help us understand the meaning of al-Jabbar. For example, in Surah Insan verse 30, "And you do not will except that Allah wills. Indeed, Allah is ever Knowing and Wise." Allah is the one who compels meaning we don't get to choose where we're born, who are parents are, our characteristics, our physical traits, or unique quirks that make us, us. We don't fully understand the intricacies of our anatomy, the beating of the heart, the firing of our nerves, the conception of a new baby. All these details of perfection which we're unaware of is because Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ has compelled it to be that way. In Surah Yaseen, "His command is only when He intends a thing that He says to it, “Be,” and it is." (36:82)
There is a second meaning of al-Jabbar as well, meaning the one who restores, resets, or fixes our brokenness. Therefore, this name can also be used in your du'a for when you want to restore or fix something. Just as he compels a thing, he puts our lives in order. In modern Arabic (جبير) jabir means cast, it heals things that are broken.
Once we come to know al-Jabbar we are subdued. We can no longer believe in our superiority if we see any kind of worldly success. We understand that He is the one who had elevated our rank. He benefits his creation, but needs no benefitting himself. This name can be a reminder to not enflate your ego, to avoid self-aggrandizement, "Thus does Allah seal over every heart [belonging to] an arrogant tyrant." (Qur'an 40:35)
We can also call upon this name for help in desperation. A cry to al-Jabbar to remedy a broken heart, marriage, or confidence. In a weak narration, "Ibn Abbas narrated: "Between the two prostrations, the Prophet would say: (Allahummaghfir li, warhamni, wajburni, wahdini, warzuqni). 'O Allah! Pardon me, have mercy on me, help me, guide me, and grant me sustenance.'  Here wajaburni means to help me, or to rectify me. Although, this narration is da'if (weak) the supplication is still very much relevant. Just the act of reciting this in between the two prostrations would be bid'ah (innovation) as it doesn't have strong evidence to support it's claim.
In another narration from Hudhaifah: He prayed with the Messenger of Allah (ﷺ) one night and he heard him say when he said the takbir: "Allahu Akbara dhal-jabaruti wal-malakuti wal-kibriya'i wal-'azamah (Allah is Most Great, the One Who has all power, sovereignty, magnificence and might.)" When bowing he would say: "Subhana Rabbial-'Azim (Glory be to my Lord Almighty)." When he raised his head from bowing he would say: "Lirabbil-hamd, Lirabbil-hamd (To my Lord be praise, to my Lord be praise)." And when he prostrated (he said): "Subhana Rabbial-A'la (Glory be to my Lord Most High)." And between the two prostrations (he said): "Rabbighfirli, Rabbighfirli (Lord forgive me, Lord forgive me)." His standing, his bowing, when he raised his head from bowing, his prostration and the time between the two prostrations, were almost the same.