I agree that 'Lunch' is the better translation. Yet I was so proud of having deducted the 'afternoon meal' by myself. Shouldn't that be also accepted, if just for encouragement to those who do like me :D
Mchana in this context definitely is "noon". I understand they usually put it as afternoon (as it strictly is from 12-14; often extended...), though technically that (aftenoon past 2 pm) would be alasiri (just as the early morning hours right before the sun rises, so 5-7, would be alfajiri) - these Arabic loan words are rarely used in everyday life.