A more thorough explanation:

The Chairman of Committees of the Whole House is a member of Parliament who leads the House of Commons when it is in committee. This means that instead of sitting as a whole group, the members of Parliament sit in smaller groups to discuss and debate specific issues.

For example, if the House of Commons is discussing a new law related to healthcare, they may sit in committee to discuss the specific details of the law. The Chairman of Committees of the Whole House would preside over this discussion and ensure that everyone follows the rules and procedures.

Another example could be if the House of Commons is reviewing the budget. They may sit in committee to review each section of the budget in detail. The Chairman of Committees of the Whole House would lead this discussion and ensure that everyone has a chance to speak and share their opinions.