。
It's wise to save money for unlikely emergencies.
Literal
By-chance's case [for-に備えて] savings do thing [topic-は] wise [copula-だ].
万が一 ('one in ten thousand,' more emphatic than plain 万一) paired with に備えて ('in preparation for') sets up a forward-looking contingency. The verdict ~のは賢明だ ('it is wise to X') is a formal life-advice frame, common in financial planning, insurance, and editorials. The ~のは nominalizes the activity and makes it the subject being judged.