Reality of Belief in the Angels
Question

What does belief in the angels mean?
Praise be to Allah.The angels form an unseen world; they were created by Allah from light and they obey the commands of Allah: 
“Who disobey not, (from executing) the commands they receive from Allah, but do that which they are commanded.” [66:6 – interpretation of the meaning] 
Belief in the angels implies four essential things: 
1 – Affirming that they exist and that they are part of the creation of Allah, subject to His Lordship and subjugated to Him. 
“…honoured slaves.
They speak not until He has spoken, and they act on His command” [21:26-27 – interpretation of the meaning] 
“Who disobey not, (from executing) the commands they receive from Allah, but do that which they are commanded.” [66:6 – interpretation of the meaning] 
“And those who are near Him (i.e. the angels) are not too proud to worship Him, nor are they weary (of His worship).
They (i.e. the angels) glorify His praises night and day, (and) they never slacken (to do so).” [21:19-20 – interpretation of the meaning] 
2 – Belief in the names of those whose name we know, such as Jibreel, Mikail, Israfil, Malik, Radwan and others – peace be upon them. 
3 – Belief in the attributes of those whose attributes we know, as we know the description of Jibreel (peace be upon him) from the sunnah (prophetic teachings), and that he has six hundred wings which filled the horizon or the sky. 
4 – Belief in the actions which we know some of them do, so Jibreel (peace be upon him) was entrusted with that which revives the heart, namely the revelation. Israfil (peace be upon him) is entrusted with sounding the trumpet-blast (to herald the onset of the Day of Resurrection); Mikail (peace be upon him) is entrusted with the rain; Malik (peace be upon him) is entrusted with Hell, and so on. 
One of the most important things that we must believe in is that every person has two angels with him who record his deeds. Allah says (interpretation of the meaning): 
“(Remember) that the two receivers (recording angels) receive (each human being), one sitting on the right and one on the left (to note his or her actions).
Not a word does he (or she) utter but there is a watcher by him ready (to record it).” [50:17-18] 
i.e., a watcher from among these angels who is present. So beware lest these two angels record anything from you that will be bad for you on the Day of Resurrection, for everything that you say will be recorded against you, and when the Day of Resurrection comes, each person’s book of deeds will be brought out. 
“… and on the Day of Resurrection, We shall bring out for him a book which he will find wide open.
(It will be said to him): ‘Read your book. You yourself are sufficient as a reckoner against you this Day.’” [17:13-14 – interpretation of the meaning]. 
We ask Allah to conceal our sins and forgive us, for He is All-Seeing, Ever Responsive. And Allah knows best. 
See: A’alam al-Sunnah al-Manshoorah, 86; Majmoo’ Fataawa al-Shaykh Ibn ‘Uthaymeen, 3/160. 
For more information see question no. 843 and 14610.