(The Protecting Associate)
The Protecting Friend, The Supporter, The Patron.
Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ is Al-Waliy (in Arabic: ٱلْوَلِيُّ), meaning the true protector. He is supportive and loves His servants, protecting them from evil. Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ wants victory for us and will guide mankind towards the path of righteousness.
From the root w-l-y which has the following classical Arabic connotations: to be near, close, nearby, to be a friend, helper, supporter, to defend, guard (lit. friendly dealing), to be in charge, to turn one toward something, to be the master, owner, lord.
Wa mai yatawallal laaha wa Rasoolahoo wallazeena aamanoo fa inna hizbal laahi humul ghaaliboon (section 8)
"And whoever is an ally of Allah and His Messenger and those who have believed – indeed, the party of Allah – they will be the predominant." (Qur'an 5:56)
al-Waliyy refers to the attribute of Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ being a close friend or ally. He wants you to know you're protected, supported, and looked after. Now, Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ is also al-Khaliq (the creator), and we understand this to mean that we are His servants. But this is just one categorization of our relationship with Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ, among the believers are a group who are also His allies. They are working in service to Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ which is one of the ways to achieve an elevated status.
But Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ affirms that to be an ally, you just need to believe.
Allaahu waliyyul lazeena aamanoo yukhrijuhum minaz zulumaati ilan noori wallazeena kafarooo awliyaaa’uhumut Taaghootu yukhrijoonahum minan noori ilaz zulumaat; ulaaa’ika Ashaabun Naari hum feehaa khaalidoon (section 34)
"Allah is the ally of those who believe. He brings them out from darknesses into the light. And those who disbelieve – their allies are Taghut. They take them out of the light into darknesses. Those are the companions of the Fire; they will abide eternally therein." (Qur'an 2:257)
Innamaa waliyyukumul laahu wa Rasooluhoo wal lazeena aamanul lazeena yuqeemoonas Salaata wa yu’toonaz Zakaata wa hum raaki’oon
"Your ally is none but Allah and [therefore] His Messenger and those who have believed – those who establish prayer and give zakah, and they bow [in worship]." (Qur'an 5:55)
In these verses, Waliy is mentioned as an ally, a working partner who ensures success for the believer. That encompasses one meaning of Waliyy. It can also refer to protection, as in the case of guardianship. For example, in Arabic, awlia (أولياء) means parents, someone who has "Wilayah" is said to be the authority, ruler, or legal guardian over someone/something. Verses from the Qur'an that reflect this quality of al-Wali as the protector are provided below:
Wa Huwal lazee yunazzilul ghaisa min ba’di maa qanatoo wa yanshuru rahmatah; wa Huwal Waliyyul Hameed
"And it is He who sends down the rain after they had despaired and spreads His mercy. And He is the Protector, the Praiseworthy." (Qur'an 42:28)
Inna waliyyial laahul lazee nazzalal Kitaaba wa Huwa yatawallas saaliheen
"Indeed, my protector is Allah, who has sent down the Book; and He is an ally to the righteous." (Qur'an 7:196)
Innahum lany yughnoo ‘anka minal laahi shai’aa; wa innaz zaalimeena ba’duhum awliyaaa’u ba’dinw wallaahu waliyyul muttaqeen
"Indeed, they will never avail you against Allah at all. And indeed, the wrongdoers are allies of one another; but Allah is the protector of the righteous." (Qur'an 45:19)
On the authority of Abu Hurayrah (may Allah be pleased with him) who said: The Messenger of Allah ﷺ said, “Verily Allah ta’ala has said: ‘Whosoever shows enmity to a wali (friend) of Mine, then I have declared war against him. And My servant does not draw near to Me with anything more loved to Me than the religious duties I have obligated upon him. And My servant continues to draw near to me with nafil (supererogatory) deeds until I Love him. When I Love him, I am his hearing with which he hears, and his sight with which he sees, and his hand with which he strikes, and his foot with which he walks. Were he to ask [something] of Me, I would surely give it to him; and were he to seek refuge with Me, I would surely grant him refuge.’” 
The believer benefits in knowing that Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ is al-Wali. He has not left any of His believers stranded. He is the best friend anyone can ask for as He has your back and will take care of all your needs. Imagine what it would feel to be part of an inner circle of a King or someone of great worldly success; you would be grateful for being in such a lucky position. You would avoid doing anything that would break the confidence of that person.
Similarly, we are privileged to have found and accepted Islam. We should feel immense gratitude and do our best to be consistent with our religious duties. We should engage in activities beloved by Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ that would raise our ranks within the inner circle of believers to grow nearer to Him.
 Sahih al-Bukhari 6502 & Hadith #38 an-Nawawi