Kana refers to Japanese Syllabaries (you might call them alphabets) Hiragana and Katakana.  If you are serious about learning Japanese, you should start by learning Hiragana and Katakana. Here is what you should know about kana:

• Hiragana and Katakana each have 46 characters.
• Each character can be written in english(roman) letters called romaji which indicate how’s it is pronounced. (hiragana す= romaji ‘su’  is pronounced like ‘sue’)
• Every kana character has a one-to-one romaji equivelant. (す is always ‘su’ in romaji and ‘su’ is always す in hiragana.  Therefore, す is always pronounced ‘sue’ unlike English where ‘t’ sounds different in in different words such as ‘the’ and ‘table’.  Therefore you always know how to spell a word in Japanese!
• Katakana shares the same sounds with Hiragana but the characters are different (romaji = hiragana = katakana  -or-  su = す = ス =  ‘sue’)
• The main difference is that Hiragana is used for Japanese words (like ‘sushi’ すし) and Katakana is used for foreign words (like ‘soup’ スープ  pronounced ‘suupu’ in Japanese)

You can learn your kana in about 10 hours or study so you should just knock that out before you do anything else.  You’ll use Hiragana more often than Katakana, so if you really must skip ahead, do yourself a favor and at least learn some Hiragana.  That way you’ll be practicing your kana as you learn your Japanese vocabulary!

A great side effect of learning Hiragana and Katakana is that if you go to Japan, amongst the incomprehensible texture of Japanese characters everywhere, you will notice things that you can actually read!  I’ll never forget when I was watching a Japanese movie and I noticed “バース” (pronounced baasu – there’s that su again) written on the ground at a bus stop.  Or when I was walking in Ginza and noticed “すしや” (pronounced ‘sushi-ya’  -or- ‘place where sushi is sold’) written above a shop.  That may not sound like much, but when everything else about Japanese is so difficult, this seems like a small victory.

Recommended Learning Materials

• A Learn Hiragana playlist from Tae Kim on youtube.
• Remembering the Kana by James Heisig (of Remembering the Kanji fame).
• Hiragana and Katakana study buddies are iOS flashcard apps.
• An Anki Kana Deck.