Yes because the voice does not make the liaison between mangent and un: you should hear "mange-T-un".
otherwise, the plural article "les" is different from the singular "le".
Pronunciation of the vowels identical to "bet" and "but", respectively.
It's very difficult to make out plurals in French. This spoken phrase can easily be mistaken as "le garcon mange un repas."
I believe Stesurf is right.
From what I remember you can pronounce the 't' of the conjugated "ent" if the following letter is a vowel though it's not common.
How am I supposed to tell the difference between plural and not?? they sound exactly the same!