For learning Kannada language it is necessary to know alphabets in Kannada. You have to know alphabets in Kannada to learn writing in Kannada language. Kannada alphabets are the building blocks of Kannada language. There are 49 characters in Kannada alphabets. Kannada alphabets are made up of Kannada vowels and Kannada consonants. The Kannada alphabets contain 14 vowels and 35 consonants. Kannada vs German gives a comparison between Kannada and German alphabets.
Kannada script is also known as Kannada writing system or Kannada orthography. The set of visible signs used to represent units of Kannada language in a systematic way is called Kannada Script. The Kannada language uses Kannada Script i.e. Kannada alphabets are derived from Kannada Script script. The script decides the writing direction of the any language, hence the writing direction of Kannada is Left-To-Right, Horizontal. Learn Kannada Greetings where you will find some interesting phrases.
Is Kannada hard to learn? The answer to this question is that it depends on one's native language. One should start learning Kannada language with Kannada alphabets and Kannada 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 Kannada is one of the language of India.