Comprehensible input means language you can understand, even when some words or expressions are new. Instead of translating every sentence or memorizing rules, you follow the meaning of what you hear or read and gradually become familiar with how the language works.
Blazing Language puts this idea into practice with interesting cultural topics told in language suited to your level. Aim to understand the main message; you do not need to catch every word.
To learn more, read Why Comprehensible Input Works.