“What a waste, huh?”

You went out to eat lunch, and the restaurant brought you a lot of food. You couldn't eat it all, and you can't take it home with you. So you have to throw it away. You say:

What a waste, huh?

what a (something)

When you say "What a waste!" it means "This is a really big waste." Similarly, if someone does something really nice, you say:

What a nice guy!

This means "He's a really nice guy."

But you can also use "What a ___" for negative things also:

What a shitty day!

This is what you say to a close friend or family member when lots of bad things happen to you on the same day.

a waste

When you have to throw away something that's valuable, like good food, you say that it's "a waste".

huh?

When someone ends a sentence with "huh?" it means that they think you're going to agree with what they said. Asking "huh" is a way to ask the listener to agree with you. So when someone says "___, huh?" you should respond "Yeah!" if you agree with what they said.