I think that the sentence means “It disables (masks) interrupts temporarily,” although I am not sure if I understand the author’s intent of the parenthesized part “(マスク)” in the original sentence correctly.
不可 here means “disabled.” I would like to add that this usage is not common. The usual word for “disabled” is 無効, and the sentence is more usually written as 割り込みを一時的に無効にする, ignoring the parenthesized part.
In addition, I think that the use of parentheses in the given sentence is nonstandard. The use indicates that マスク is either an explanation or a paraphrase of 不可, but explaining 不可 as “mask” or “masking” is, well, a type error. I think that what the author wanted to say is something like
where マスクする (to mask) is another way of stating 無効にする (to disable).