Probably should explain a little bit about these.
Hiragana is one of the three Japanese alphabets* It's syllabic, which means each character represents a sound. There are 46 characters and this alphabet used for native Japanese words. There's loads of resources online if you're interested in learning more.
"Ka" is an audible question mark-which can be difficult in conversation. If you're a beginner, you know when someone is asking you a question...but can have no clue what they're asking for.
For some reason I think that the "ka" character is supposed to represent a man flexing his arm muscles. Stuff like that is why this alphabet is for my reference only.
*or four, if you include romaji-English letters.