Languages have homographs (words spelt the same), homophones (words pronounced the same) and homonyms (words spelt and pronounced the same).
In German, a particularly tricky set of homophones (two of which are also homographs) are sie (3rd person singular feminine), sie (3rd person plural) and Sie (formal 2nd person singular or plural). In writing, one can at least distinguish between the formal Sie and the others, and in every case where sie is the subject the verb’s form will help you distinguish between singular and plural. Other than that, context is king and sometimes even with context sentences remain fully ambiguous.
German is not a particularly special language here; English has you (2nd person singular and plural, subject and object form), too. So if I took the following German examples, they translate identically into English, too:
Ich sehe dich nicht.
Ich sehe euch nicht.
I do not see you.