Final answer:
A flowmeter is essential in regulating the amount of oxygen that a client receives, ensuring the delivery of the correct oxygen flow rate as prescribed by the healthcare provider.
Step-by-step explanation:
The teaching about a flowmeter that is important for the nurse to provide to a client using oxygen is that it regulates the amount of oxygen received. This is essential to ensure the client is administered the correct flow rate per the health care provider's orders and to avoid complications arising from too much or too little oxygen. While other apparatuses like a pulse oximeter can measure oxygen saturation in the blood and indicate the effectiveness of oxygen therapy, the flowmeter's function is specifically to control the oxygen flow rate to the patient.