The Most Strong, Perfect Power, The One with inexhaustible strength.
Allah ٱلْقَوِيُّ is Al-Qawiyy (in Arabic: ٱلْقَوِيُّ), meaning the one who commands all power and whose strength is unparalleled to anything else. His strength is truly unlimited and inexhaustible. Man’s strength does not compare to that of Allah the Almighty.
From the root q-w-y which has the following classical Arabic connotations: to be strong, vigorous, potent, to be robust, hardy, sturdy, to have sufficient strength or power, to prevail over.
The name al-Qawiyy (sometimes written as al-Qawi) is mentioned a total of nine times in the Qur'an. It refers to Allah's attribute of being the strong. The one who has perfect power. He is eternal, death is not something which touches Him. He does not sleep or grow tired, "Neither drowsiness overtakes Him nor sleep." (Qur'an 2:255) He is all-seeing, omnipresent, the all-wise and knowing.
It's an important attribute to understand. It's because He has perfect strength we rely upon Him for our success. Given a choice between two leaders, you would likely choose the one whose power was unmatched. He could not be beaten, so you would be more trusting of Him because He could provide comfort and protection from any danger that threatens you. Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ is al-Qawi, meaning the all-powerful and all-strong. There is nothing remotely close to matching His power; therefore, He is the only one we should rely on and trust (concept of tawhid).
Qaalat ihdaahumaa yaaa abatis taajirhu inna khaira manistaajartal qawiyyul ameen
"One of the women said, 'O my father, hire him. Indeed, the best one you can hire is the strong and the trustworthy.'" (Qur'an 28:26)
Maa qadrul laaha haqqa qadrih; innal laaha la Qawiyyun ‘Azeez
"They have not appraised Allah with true appraisal. Indeed, Allah is Powerful and Exalted in Might." (Qur'an 22:74)
Allahu lateefum bi’ibaadihee yarzuqu mai yashaaa’u wa Huwal Qawiyyul ‘Azeez (Section 2)
"Allah is Subtle with His servants; He gives provisions to whom He wills. And He is the Powerful, the Exalted in Might." (Qur'an 42:19)
The believer benefits in knowing that Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ is al-Qawiyy. He has unlimited capability and should be feared in the sense that if He chose to go against you, you would be helpless. In the Qur'an, "If Allah should aid you, no one can overcome you; but if He should forsake you, who is there that can aid you after Him? And upon Allah let the believers rely." (3:160)
Those who fear Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ should not fear those who, on the surface, seem intimidating and powerful. If you see yourself as being in the power of Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ, you don't need to fear others. This insight, once internalized, can bring you strength and courage to stand up against injustice. The pairing of the names al-Aziz (The Mighty) and al-Qawiyy (The All-Powerful) is often mentioned in tandem as a reminder of Allah's support for the believers against those who are corrupt and unjust. These next two ayat illustrate this point:
Laqad arsalnaa Rusulanaa bilbaiyinaati wa anzalnaa ma’ahumul Kitaaba wal Meezaana liyaqooman naasu bilqist, wa anzalnal hadeeda feehi baasun shadeedunw wa manaafi’u linnaasi wa liya’lamal laahu many yansuruhoo wa Rusulahoo bilghaib; innal laaha Qawiyyun Azeez
"We sent aforetime our messengers with Clear Signs and sent down with them the Book and the Balance (of Right and Wrong), that men may stand forth in justice; and We sent down Iron, in which is (material for) mighty war, as well as many benefits for mankind, that Allah may test who it is that will help, Unseen, Him and His messengers: For Allah is Full of Strength, Exalted in Might (and able to enforce His Will)." (Qur'an 57:25)
Wa raddal laahul lazeena kafaroo bighaizihim lam yanaaloo khairaa; wa kafal laahul mu’mineenal qitaal; wa kaanal laahu Qawiyyan ‘Azeezaa
"And Allah repelled those who disbelieved, in their rage, not having obtained any good. And sufficient was Allah for the believers in battle, and ever is Allah Powerful and Exalted in Might." (Qur'an 33:25)
Supplication of Prophet Muhammad ﷺ:
It was narrated that Abu Musa said: "The Prophet ﷺ heard me saying: 'La hawla wa la quwwata illa billah (there is no power and no strength except with Allah).' He said: 'O 'Abdullah bin Qais! Shall I not tell you of a word which is one of the treasures of Paradise?' I said: 'Yes, O Messenger of Allah.' He said: 'Say: La hawla wa la quwwata illa billah (There is no power and no strength except with Allah).'"
 Sahih (Darussalam) Sunan Ibn Majah 3824