。
The budget has to balance.
Literal
Budget [topic-は] balance [subject-が] take-[state-ている]-[must-なければならない].
均衡がとれる ('balance is struck, equilibrium is achieved') is an idiomatic collocation — 均衡 is the noun 'balance' and とれる is the potential/passive of 取る used intransitively: 'balance comes to be taken.' Common in financial and formal register. ~ていなければならない stacks the resulting-state ~ている with the obligation ~なければならない — 'must be in the state of balance.'