。！
Basically I need money. Lend me some!
Literal
Essentially money [subject-が] necessary-[explanatory-んだ]. Lend-give-me-[emphasis-よ]!
金が必要だ = 'money is necessary / I need money.' The subject-necessity pattern is the standard Japanese way to express needs. 貸してくれよ uses the casual request form ~てくれ + よ for intensive emphasis. Desperate, casual plea.