Learn German: Studenten bekommen eine Ermäßigung.

No, bekommen is a classic false friend. It looks like "become," but it actually means "to get" or "to receive." To say "become" in German, you must use the verb werden.

Is Studenten plural here, or is it a singular noun with an ending?

Here, Studenten is the plural word for "students." However, it is a great reminder that der Student is a "weak noun" (n-declension). This means even in the singular, it takes an -en ending in every case except the nominative, such as in Ich frage den Studenten (I ask the student). Because it is the subject of this sentence, we know it is plural.

How can I remember or break down the word Ermäßigung?

Breaking it down makes it much easier! It comes from the noun das Maß (measure or amount). When you add the prefix er- and the suffix -ung, it becomes a noun describing a process. An Ermäßigung is literally the act of making an amount more moderate, which translates perfectly to a discount or price reduction.

Why is it eine Ermäßigung?

Almost all German nouns ending in -ung are feminine. Because the discount is the direct object that the students are receiving, it is in the accusative case. The feminine accusative form of the indefinite article is eine.