1. To be completely clean. English = (be) spotless.
2. To be completely clean, or to be not mixed with anything else and containing no harmful substances. English = (be) pure.
3. To be or to make something easy to understand, see or hear, or to be obvious and impossible to be mistaken about. English = (be) clear; clarify.
4. To be correct or proper in every way possible, especially with reference to the answer to a question or problem. English = (be) precise, (be) accurate, (be) exact.
5. In a scientific context (mathematics, information, measurements, etc.), used to describe data, procedures, experiments, etc. which are correct and exact in all details. English = (be) accurate.