For learning Hindi language it is necessary to know alphabets in Hindi. You have to know alphabets in Hindi to learn writing in Hindi language. Hindi alphabets are the building blocks of Hindi language. There are 44 characters in Hindi alphabets. Hindi alphabets are made up of Hindi vowels and Hindi consonants. The Hindi alphabets contain 11 vowels and 33 consonants. Hindi vs German gives a comparison between Hindi and German alphabets.
Hindi script is also known as Hindi writing system or Hindi orthography. The set of visible signs used to represent units of Hindi language in a systematic way is called Hindi Script. The Hindi language uses Devanagari i.e. Hindi alphabets are derived from Devanagari script. The script decides the writing direction of the any language, hence the writing direction of Hindi is Left-To-Right, Horizontal. Learn Hindi Greetings where you will find some interesting phrases.
Is Hindi hard to learn? The answer to this question is that it depends on one's native language. One should start learning Hindi language with Hindi alphabets and Hindi phonology.
Time taken to learn any language that is mentioned here is the approximate time required to learn specific language for the person who is proficient in English. You can also go through all Indian Languages and find if Hindi is one of the language of India.