Oooh, I get what you are saying. Yeah, they have this thing completely expanded.
What they are calling monographs in the upper left are 'single character', they are the 五十音 - the 50 sounds (46) - this is the standard table. In the upper right are 'double character' digraphs - what the Japanese call youon 拗音 - the are palatized sounds derived from the い column. You are expected to glide the sounds together - for instance if you say ri + yu together fast the i becomes muted and you get ryu. These are not characters in their own right, it is just meant to make things easier, and are good to learn as a unit of sound. The bottom left are the voiced/plosive versions of the sounds, they are what take the tenten (dakuten), or maru (handakuten). The lower right are the voiced versions of the youon.
Small little walk through:
These are all the same character.
ひ, び, ぴ - hi, bi, pi - sounds like he, bee, pee. The first one is a pure sound, the second one is voiced (vibrate your voicebox while saying hi and it will sound like bi), and the third one plosive (pucker your lips and quickly open while saying hi and it will sound like pi)
ひゃ, ひゅ, ひょ, - hya, hyu, hyo - ひ glide to や, ひ glide to ゆ, ひ glide to よ.
You can also combine them so that ぴょ - plosive hi, glide to yo - pyo.