"bint" can mean both "daughter" and "girl," but "ibn" can only mean "son," by the way. Also, ابن is one of ten nouns in Arabic (not derived from verbs that is) that start with a consonant cluster. Since this is not allowed at the beginning of an utterance, we add an 2i- sound at the beginning of the word, but only if it's the first word of the utterence. That's the sound represented by the alif without the hamza at the start of the word. Otherwise, that alif is silent. Four of the ten words aren't ones you're likely to encounter in your preliminary interactions with Arabic, but the common ones are: ابن ابنة (son, daughter), اثنان اثنتان (two [masculine], two [feminine]), اسم (name), and امرأة (woman), for a total of six words.
The audio of وَابْن sounds like : "waben". Isn't it supposed to be "wa-2ibn"?
That's what I'm saying, this is correct. It is supposed to be "wabn" and not "wa-2ibn." It is only pronounced "2ibn" when there is nothing before it.