Devanagari script is written in Sanskrit, Marathi, Konkani, Nepali, Maithili etc. However, in modern Hindi languages, some of the alphabets do not use to construct words or letters of Hindi Language. come out of the place, they are called ‘ Hindi vowels‘.
When pronouncing the letters, when the breath, the throat, the palate, etc.See: Hindi Alphabets and Pronunciation in English.Hindi 52 Alphabets: Hindi Consonants ( 39) + Hindi Vowels ( 13) =52.