To put a moratorium on something means to ban or prohibit it temporarily. In legal language it also means to authorize a delay in payment of a debt.
The plural can be either moratoriums or moratoria. As with all adopted Latin, adding an s is perfectly acceptable, but there will always be some who prefer the Latin conjugation.
The word was coined in the late 19th century with its legal definition. It comes from the Latin verb moratorius ‘delaying’, and was written in italics for almost 50 years before being adopted as a fully English word. Over time it gained the more common use meaning.
See the ngram below to track moratorium’s rise and fall of usage.