This is the most important question to ask when you’re trying to understand halal. Halal literally means “permitted” or “lawful” in Arabic, and it refers to what is allowed in Islamic dietary laws. The opposite of halal is haram, which means forbidden. This gets a little confusing because some people use the term haram when they really mean non-halal or not permitted by Islam. For example, pork is haram for Muslims because it’s considered unclean; however, the word “non-halal” would be more appropriate here since it doesn’t specify why someone can’t eat pork (it’s just unclean).
A simple way of understanding this distinction between words like non-halal and haram is that if something isn’t specifically prohibited by Islam then you should assume that it’s halal unless otherwise stated.