"bineiah kabira" or "bineiatun kabira"? Where is this "tun" from? Can someone help me to understand?
with proper Arabic, it should be (bináyatun kabírah) or (kabíratun) - this word is at the end so the vowel -un can be dropped.
Here we have a noun (feminine) which ends in Ta-Marbúta ة . This letter merges H and T in a single form. This is because in Arabic, there are some nouns that end in "H" usually, but when are moved with vowels and come in the beginning or in the middle of a sentence, eventually this "H" turns to "T" (just a property of some words and majorly feminine words). So, instead of changing the spelling of such words from H هـ to ت ... this letter, Ta'-Marbúta, was invented to merge the two into one.
The -un sound is called Nunation or Tanwin. It has many uses and signifies some aspects but for the time being ...... and in this instance, just imagine it is equivalent to the English a/an article (i.e. the indefinite article). Thus, a word in Arabic, if not defined with AL in the beginning, then it is marked as indefinite by this Tanwin at its end.