1. To be based on facts and on things that really have happened and are not invented. English = (be) factual.
2. To have no doubt that something is in agreement with the facts, to have no doubt that something is true; to be firm and clear, and be unlikely to be changed in your opinion. English = (be) certain, (be) definite.
3. To have the ability to perform a task without making a mistake; to have the quality of giving a true idea of what someone or something is like. English = (be) accurate.