This is a text generator which generates text using Markov chains. The resulting text will very likely be gibberish, but it will be gibberish resembling the original input. Essentially, the generator looks at which characters are next to each other in the input, and how often, and uses this to generate output text.
Since Markov chains are all about probabilities, the generated text is random, and will likely be different each time (for long enough inputs). This page does not encrypt text, or scramble it. Two letters can be next to each other in the output if and only if they are next to each other in the input.
Longer inputs (or more precisely, inputs with more repeated letters) tend to produce longer outputs. If no character appears more than once in the input, then the output will always be the exact same as the input.
The generator currently supports two "modes": sentence and word. Word mode always generates individual words, and sentence mode generally produces longer output. However, since the generated text is random, word mode might well generate a 30-character-long word (if the input is large and repetitive enough), and sentence mode could produce only a few letters.