An "inscription" is a set of memorable or important words that are written or etched onto something durable. The writing can be on something like a tombstone or sculpture or even in a book.
The original word in Latin (from the past participle "inscribere") had a more informal meaning, as it basically just meant "to write." In modern times, it is a bit more formal, implying writing something of importance in remembrance of somebody or as a significant message for someone. In Middle English, in fact, it referred to the text at the start of a book that was dedicated to a particular person.