Ett äpple, äpplet, äpplena, why its äpplena and not äppleta?
You missed one word: ett äpple - äpplet flera äpplen - äpplena
Oh that way, tack!
Is this the standard indefinite/definite pluralization for ett-words ending in a vowel?
Yes.
Difference between "applet" and "applena"?
Äpplet = The apple
Äpplena = The apples
Thank you.