shortened braille (actually called contracted braille) basically works like this:
you have six dots which in various combinations are used to make up 63 different combinations.
Obviously you do have the basic alphabet, punctuation signs etc and there is a number sign which is put in front of letters to make numbers, so the number one is written as a number sign followed by the letter a, ten by number sign followed by A and J and so on.
But because braille is so bulky it has to be shortened otherwise it would just take up too much space. So different letter combinations have been used to represent different words/parts of words.
So for instance, the letter B, written within a word is obviously just that - the letter B. But the letter b written on its own represents the word "but", the letter C represents the word "can" and so on.
It gets more complicated in that there are combinations that for instance represent the letter sequence "ation" and "ity" so that when, for instance writing the word "city" you write the letter C, and then a two symbol combination for "ity" thus meaning that "city" is just a three symbol combination rather than the four letters that it is.
So e.g. if you write out community it is written as two dots which represent the "com" then mun" then the "ity" contraction, meaning that you never see the word community written out.
That's a bit of a long-winded explanation but that's the gist.