Learn German: Wir müssen den Flüchtling schützen.

Nouns ending in the suffix -ling are almost always masculine. Because the verb schützen (to protect) requires a direct object, the noun takes the accusative case, changing the article to den.

How would this sentence change if we were protecting multiple refugees?

It would become Wir müssen die Flüchtlinge schützen. Masculine nouns ending in the -ling suffix have a very regular plural form: you simply add an -e to the end.

How does the suffix -ling help us understand the meaning of the word Flüchtling?

The suffix -ling is often attached to verb stems or adjectives to describe a person associated with that action or trait. Here, it is combined with the stem of flüchten (to flee) or die Flucht (the escape) to mean a person who flees, similar to how English uses the suffix -ee in refugee or escapee.

If we wanted to say what we are protecting the refugee from, how would we add that to the sentence?

You would use the preposition vor followed by the dative case. For example, Wir müssen den Flüchtling vor dem Krieg schützen means We must protect the refugee from the war.