Questions about the basic lexical category known as the "noun". In layman's terms, a noun is commonly considered to be a "person, place, or thing (including abstract concept)". Nouns can be modified by articles ("ein", "der") or prepositions ("nach", "unter") and can be the subject or object of a sentence.
See also: proper-nouns.
If your question is about a different kind of word, please use verb, adjective, adverb etc. instead.