"We are going to have a good meal."
Translation:Nous allons prendre un bon repas.
It's just the way English-speaker and French-speaker speak. If you say Nous allons avoir un bon repas, it means that you are going to possess that meal. On the other hand, in French, it's pretty common to say Je vais prendre un café (literally I'm going to take a coffee) to say I'm going to drink a coffee). Therefore, as ripcurlgirl said to have a meal = prendre un repas
In any of these languages it would be far better to put the English in the foreign form, much easier to learn. Eg if the question was asked in english as it would be in the relevant language it would be easier to translate instead of trying to mentally rearrange it. I know not everyone on duo is an english speaker but for those who are just try altering the way you speak English.
I'm a french native speaker ( I completed the French to English tree and I am doing the reverse tree ) I too answered " Nous allons avoir un bon repas " " Nous allons prendre un bon repas " sounds a bit odd to me , I've never heard this . " Nous allons manger un bon repas " is more usual ( very usual : " On va bien manger " ... ) But " On va prendre un café " is usual ...
"On va bien manger" is common for sure but not very elegant. The reason is that, preferably, "manger" should have an object. "On va manger un bon rôti."
"Prendre le petit déjeuner, prendre un repas, prendre un café, prendre le poulet au riz...." all these are translations to and from "have".
For main meals, please use "déjeuner" or "dîner" depending on the time in the day: "On va bien déjeuner/dîner."
If you say "je prends le déjeuner/dîner", it means you bought it and will take the bag or box back home.