Plural-only nouns
English has words that only exist in the plural, like "scissors" or "pants". German has them too, but they often do not match the English ones. A group of German nouns only exists in the plural form. These are called plural-only nouns.
When English speakers see a word translated as "vacation" or "measles", they often try to use a singular verb because the concept feels singular in English. In German, however, these plural-only words require plural verbs, plural pronouns, and plural articles.
Some of the most common plural-only words refer to groups of people. Words like Leute (people), Eltern (parents), and Großeltern (grandparents) always take plural verbs. You cannot use these to talk about a single person. Similarly, when talking about personal items, Habseligkeiten (belongings) is strictly plural.
Words related to finances and time off frequently fall into this category. Kosten (cost) and Alimente (alimony) are always plural in German, even when English uses a singular noun. Time off is also treated as a collection of days, meaning Ferien (vacation) and Flitterwochen (honeymoon) take plural verbs.
Certain illnesses are a major trap for English speakers. In English, we say "measles is contagious" using a singular verb. German treats Masern (measles), Pocken (smallpox), and Windpocken (chickenpox) as plural nouns. They describe a breakout of many spots, so they demand a plural verb.
Mountain ranges and certain countries made up of regions or islands are plural. Words like Alpen (Alps), Pyrenäen (Pyrenees), Niederlande (Netherlands), and Philippinen (Philippines) must be used with the plural article die.
Because these words only exist in the plural, you cannot simply drop a letter to create a singular version. If you need to single out one item from the group, you must use a completely different word. For example, if you want to mention one of your Geschwister (siblings), you refer to your brother or sister. To talk about one parent instead of your Eltern, you can use the word Elternteil.
When learning a new German noun, take note if it is plural-only. You must always pair these words with plural articles, plural pronouns, and plural verbs, even if the English equivalent is a singular concept.