Learn German: Plant ihr euren Balkon? - Are you plural planning your balcony?

Balkon is a masculine noun (der Balkon), and in this sentence, it is the direct object (the thing being planned). In German, this is called the accusative case. Masculine words in the accusative get an -en ending, so the base word euer (your) becomes euren.

I noticed the spelling of euren. Shouldn't adding -en to euer make it eueren?

You would think so! But to make it easier to say, German drops the middle e when adding endings to euer. So instead of eueren, it shrinks down to euren.

How do I know if I should use ihr or euer for the plural "you"?

Use ihr when you mean "you" (the subject doing the action). Here, ihr are the people doing the planning. Use euer (or its variations like euren) when you mean "your" (showing possession), like your balcony.

Isn't ihr also the word for "her" or "their"? How do we know which one it is here?