N5 is the lowest level of the Japanese Language Proficiency Exam (JLPT) and is defined by the ability to understand some basic Japanese. I will post more details once I get some more time.
Requirements of N5
One is able to read and understand typical expressions and sentences written in hiragana, katakana, and basic kanji.
One is able to listen and comprehend conversations about topics regularly encountered in daily life and classroom situations, and is able to pick up necessary information from short conversations spoken slowly.