問題は私達が金不足ということです。

。

The problem is that we're short on money.

Literal

Problem [topic-は] we [subj-が] money-shortage [という thing-ということ] [copula-です].

金不足 ('money shortage') is a compound: 金 ('money') + 不足 ('shortage, insufficiency'). The 不- prefix is the negation prefix. The whole clause 私達が金不足 is framed as a 'という' nominalized content.