If it helps, pige is singular, the n makes it 'the' and the erne makes it 'the' in plural form
How do you know wheter 'de drikker mælk' is translated as 'they are drinking milk' or 'they drink milk'?
I believe it is because they don't use the present continuous like we do, it's just "they drink milk".
The plurals and 'the boy', (or girl), are so hard to figure out - looking at the comment of Dark_Devin - so if pige is singular for 'girl' - what is 'girls' Also, what are the Danish words for just 'boy', and then just 'boys'
Pige = girl Piger = girls Pigen = the girl Pigerne = the girls. Just put the er and en suffix together