Every substantive with et and one syllable are in plural without -er ending.
en katt - katter
et brev - brev
The speaker always seems so excited about newspapers, ha! "Anviser!"
Did this get updated to include brever? It marks it as correct for me. Bit weird, if brever isn't actually a word.
"aviser og brever" is not this the correct way?
No, "letters"= "brev", no -er ending.
This is true for most monosyllabic neuter words in indefinite plural.
There are some exceptions, like 'salt'. But in general there is no ending for these.
'salt' is an uncountable noun, so 'salt' is just one type of salt, while 'salter' means different types of salt.