"I am drinking beer."
Translation:Ich trinke Bier.
tl;dr - that's like saying 'I drinks'. It's wrong.
Yeah, that would have been marked incorrect. Let me teach you something called conjugation, which you can already do in English:
You know how you can say "I am" and "you are", but not 'I are' or 'you am'? That's because the verb form ("am" and "are" are forms of the verb "to be") needs to match the pronoun ("I" and "you" are pronouns). This is also true for German, although way the verb changes is a little bit different, and there are a few more forms to memorise. Changing the verb form to match the pronoun is called conjugation.
English has just 2 forms for "to drink":
- "I/you/we/they drink"
- "he/she/it drinks"
German has 4 forms for trinken (usually there are 5 forms for each verb, but sometimes the forms are the same):
- ich trinke
- du trinkst
- er/sie/es trinkt
- ihr trinkt
- sie/Sie/wir trinken
You don't need to memorise them all just yet, but just notice that there are different forms to go with the different pronouns. It's much more helpful to remember that du goes with the -st ending than to think of trinkst meaning "drink" (because that doesn't work with "I"/ich, for example).