I think you mean Hålla tal. Which means: make a speech?
I am not entirely sure what it is supposed to mean either. The expression in itself, hall av tal, is grammatically possible, but it sounds very abstract and is not easy to understand. Hall can mean "hallway", and tal can mean "speech", "speach" or "number" as in "the number 20", or "sum" as in "work out a sum".
Can you please give a little bit more context? If you found it in a text, can you please give us the whole sentence, or even some lines before and after this expression?
Hall av tal i think I could translated as "Aditorium"
but if the word hAll in the vowel A has as a small O up , it means : part, way, direction ...I hope than that helps you a little bit ...I am trying to learn this language, too.