There are some such words in North English and Scots. "ken" and "kjenne", "kirk" and "kirke" are other examples. Insular Scots has even more. Even in Standard English there are quite a few words with Old Norse origins:
The most common is "are".
It sounds like barn, it's just a veery open a.
They're used in different dialects, but the meaning is the same. 'barn' is the most common word in Eastern Norwegian dialects, and is the one taught in this course.
Note that the adjective 'unge' refers to youth, so 'barn og unge' means 'children and [youth/young people]'. This usage of 'unge' is different from the noun 'en unge' :)