It means those credentials are in the public domain. If you use that password anywhere else, those accounts are at high risk.
Knowing the context (like an alert or a file you found) can help me give you more specific advice. 135k Combo List.txt
In some online communities, "piece" can refer to a specific part of a larger leak or a "vouch" for the file's validity. Why does this matter to you? It means those credentials are in the public domain