Welcome in the first place, we are friendly so don't worry.. Regarding to silencer threads ext... Most are 1/2"UNF" universal fine" others are slip ons which fix with grub screws.. Available in most diameters.. Others are custom slip on.. For tapered or shouldered barrel profiles..
You also get silencer adapters which are basically a slip on with a thread for a threaded silencer.
On some Asian and cheapie airguns you might find an M10 fine or similar but very very uncommon, only know of two cases.