。
The budget is tight.
Literal
Budget [subject-が] limit-[passive-ている]-[polite-ます].
限られる ('to be limited') is the passive of 限る ('to limit, restrict'), commonly used in its state-form 限られている to describe something that's constrained — time, resources, people. The が marks 予算 as the grammatical subject, contrasting with は which would topicalize it. A short, practical workplace statement.