I make mistakes very often when learning swedish/russian/polish/german/dutch/french and should translate it to english and do not know its rules.
Its just based if its ett or en. For example: you say "en man" but with apple you say "ett äpple". There's no rule, it just exist.
Why must be the beef, beef without the not corect? English is not my first language, maybe I will understand its rules until the end of Swedish course