From the WaniKani FAQ:
What will I learn by using WaniKani?
Currently, we have plans to take you through most of the Joyo kanji with various additions and subtractions. This includes the meanings and common readings of these kanji. On top of this you’ll be learning an estimated 5,000 Japanese vocabulary words.
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Don’t be too discouraged when you start off, as it seems like it takes forever to get past radicals and get to Kanji and Vocab, but they will start coming in a lot quicker. If you actually know all the Kanji here though it will likely take quite a long time before you hit new stuff, but it will certainly help reinforce all the ones you learned here.