Fruit

proper

I haven't seen a proper mango here.

In this case "proper" can be replaced with "real," "normal" or "regular."  Notice the following:

1. She finally bought a proper pair of shoes and stopped wearing sandals everywhere.
   
2. Do you have a proper plate?  I hate plastic plates.
   

variety

There are a variety of mangoes.

A "variety of mangoes" is a number of different types of mangoes.Notice the following:

1. He likes food from a variety of countries.
   
2. We have a variety of different games.
   

raw

How do you eat mango, do you eat it raw?

To eat something "raw" is to eat it without cooking it.  Notice the following:

1. He eats his meat almost raw.
   
2. Do you cook the carrots or eat them raw?
   

juice

Do you have mango juice?

"Mango juice" is the liquid of the mango and the fruit mixed together to make a liquid.  Usually juice is made from fruits or vegetables.  Notice the following:

1. Do you like tomato juice?
   
2. He drinks orange juice every morning with his breakfast.
   

popular

Is mango juice popular?

If something is "popular" a lot of people like it.  Notice the following:

1. That band has never been popular.
   
2. She was very popular in high school.