Assalam O Alaikum W Rahmatullahi Wa Barakatuh,
Sister the word “wazifa” is no where to be found in Quran or sunnah. People of sub continent have innovated this into the religion. Anything which is not part of our religion will be rejected. I will tell you a very simple rule, always look for what’s the source of information. Is it coming through an authentic source such as Quran and Hadith? If not then it is best for you to stay away from these innovations.
Pray 5 times and ask Allah Subhanahu Wa Taala for anything which you need. If that’s not enough, get up for Tahajud and make dua at that time, you can make dua in your own language and inshallah Allah will make it easy for you.
Regarding the meaning of “Subbuhun” it is from the word subhan. We often say subhan Allah which means glory be to Allah or in simple word it means Allah is free from any mistake and He is perfect. Subbuhun means “the perfect” or “most glorious”
There is a Hadith narrated by our mother Aisha (ra) that Prophet Muhammad ( peace be upon him) often used to make following supplication while bowing or prostrating:
'Subbuhun Quddusun Rabbul-mala'ikati war'ruh’
So apparently half the wazifa comes from this Hadith and rest comes from the names of Allah Subhanahu Wa Taala. Why you have to say it 21 times and did prophet peace be upon him or his companions did this? Answer is simply NO.
Anyways, there is no basis of such wazifa in sunnah and as I suggested that it is best to make dua during your prayers and inshallah Allah will make things easy for you.
Ma’a Salama
