Giving a Power of Attorney means that the person you appoint will have legal authority to manage your financial affairs according to your instructions.
If you are travelling overseas, you might want to give your attorney access to your bank accounts so that they can manage your finances and pay the bills while you are away. Alternatively, you might want to make a Power of Attorney so that someone you trust can manage your affairs in case you lose the ability to do so yourself.
Making a Power of Attorney does not mean that you will lose control over your financial affairs.Your attorney will simply have formal authority to manage your financial affairs. You can cancel a Power of Attorney at any time provided you have the capacity to do so.