"We are going to listen to the radio tonight."
Translation:Dyn ni am wrando ar y radio heno.
am can be used in several contexts, more in some dialects than others. In this example it is being used to create a simple future - not a very common way if doing it, but you may meet it, especially in speech and especially in north-west Wales, I think.
Which notes section is "am" mentioned in? It keeps showing up and I have no idea how to use it, no idea if it's dialectal, and no idea what it really means. :P
Just use Dyn ni'n mynd i wrando... instead for this particular phrase. Just be aware that you may sometimes come across am being used to create the same meaning.
As I explained in my earlier answer, am is a preposition with a number of uses.
Please correct me if I am wrong ... the "am" acts as the English word "for" ... giving the meaning, "We are for listening to the radio tonight."
If you are "for" or "in favour" of doing something, then it is likely that you are going to do it.
Here, am can have a meaning of wanting to do something, or of going to do something. It does not really translate very well into an English word - it is more of an idiomatic usage.