Explain (verb)

1. Make (something) clear or understandable by describing it in more detail or revealing relevant facts or ideas.
2. Account for or justify (an action or event) by giving a reason or an explanation.
3. Provide a reason or justification for (a statement or theory).

Origin:

Middle english: from old french esplaign-, lengthened stem of esplaindre, from latin explicare, from ex- "out" + plicare "fold".

Examples:

1. Can you explain how the machine works?
2. He explained his absence by saying he was ill.
3. She explained the reasoning behind her decision.
4. He explained the problem with a simple example.
5. The teacher explained the lesson to the students.