Ah okay, so "høre på" means "listen to" whereas "høre" means "hear"? Takk!
Kunne man også sier: 'Han vil lytte på radio.' ?
Could you also say: 'Han vil lytte på radio.' ?
Lytte til radio. That's more specifically the physical action of listening, however.
Assuming you meant that to be an "å", it's because the "to" in the English sentence is a preposition and not an infinitive mark.
There is also a world of difference between "(å) høre" and "(å) hore", so this is one of those cases where it really is worth going the extra mile and using those Norwegian characters. If you cannot access them on the device you're using, you can transcribe them like this in the sentence discussions:
æ = ae
ø = oe
å = aa