German nouns are masculine, feminine or neuter — der, die or das — and the gender decides the article, the adjective ending and the pronoun you use later. It is the first thing learners try to shortcut and the first thing that blocks them at A2.
There is no reliable way to work the gender out from the object. A table is masculine (der Tisch), a door is feminine (die Tür), a window is neuter (das Fenster), and nothing about tables or windows explains it. So stop trying to derive it and change how you store it: never learn a noun without its article. Not "Tisch = table" but "der Tisch = table". The article is part of the word, exactly as the spelling is.
A few endings are reliable enough to lean on:
- -ung, -heit, -keit, -schaft, -tion, -ie are feminine. die Wohnung, die Freiheit, die
- Universität, die Information.
- -chen and -lein are neuter, always, whatever the thing is. That is why das Mädchen —
- "girl" — is neuter: the ending wins over the meaning.
- -er for a person who does something is masculine: der Lehrer, der Arbeiter.
Plurals are a separate fact to learn, again with the noun, because German forms them several ways: der Tisch → die Tische, die Tür → die Türen, das Fenster → die Fenster (unchanged), das Buch → die Bücher. In the plural the article is die for every gender, which is the one piece of good news in this lesson.
Write new vocabulary in three parts from today: article, noun, plural. der Tisch, die Tische. Twenty nouns stored properly are worth more than a hundred stored as bare words, because the bare ones will have to be relearned when you meet the cases.