Yes, they both translate to 'a/an(/one)' in English.
et is the indefinite article for neuter nouns.
en is the indefinite article for masculine nouns.
ei is the indefinite article for feminine nouns.
PS: All feminine nouns can also be declined as if they were masculine, using the masculine declination pattern, so you can choose to use en for feminine nouns as well.
I had the same problem too. You should bite the ends of words, I.e. make the ends of words sort of melt together, e.g. piger = "piie" or something like that. Give it a shot, it worked for me! ;)