KA is two wavy lines laid parellel with a line joining the two of them at their center.

To some ka represents two rivers (wavy lines) joined by a center line. 

         

To others, it represents to spirits(wavy lines) joined by a center line.

So when you know what the syllable of KA does within Filipino words, that is, creates a relation or connection ((kapatid(sibling), kasintahan(loved-one), kapwa(fellow), kalakbay(fellow journeyer). ka-klase(classmate)). 

So when you see the meaning of KA with its actual baybayin symbol, it seems immensely appropriate.

KA also means connection between the heaven and earth:

courtesy of Akopito

The following text is from Akopito’s blogpost:

Ka
So basically it was the two Gods agreement is also the beginning of the formation of the world.Ka also represent ‘Kauban‘ (United)- it was when the Two Gods agree to unite is also known as the beginning of the formation of the world.Ka also represent ‘Kalibutan‘ (The World) – The world was form when the two Gods loss their grandchildren, so they created a new Life a new Race now known as the beginning of the Human race.

Ka from ‘Katawo-an’ (Human race) – the last creation by the two Gods, the Gods created the Human race so that they can take care of the world that they built.

Kaptan – represent the red line above
Maguayen – represent the blue line below
The yellow line between the two gods represents ‘Life, given by the two gods to the human race also the formation of the world so Human race can live with it.

To read the legend or the Story Behind the KA Character read more at Akopito’s blog.
http://plus24seven.weebly.com/1/post/2011/02/theory-on-the-origin-of-the-bisayan-characters-and-the-story-behind-the-ka-character.html

Akopito’s baybayin interpretations come from a visayan standpoint but still fit closely in with other Philippine origins and viewpoints.