僕が隠れて君が僕を見つけるんだよ。わかった。

。。

I'll hide and you find me, okay? Got it?

Literal

I [subject-が] hide-and you [subject-が] I [object-を] find [explanatory-んだよ]. Understand?

A child's hide-and-seek instruction! 隠れる ('to hide oneself') is the reflexive/intransitive version — the transitive is 隠す ('to hide [something]'). 僕が隠れて(subject of subordinate clause) + 君が僕を見つける (subject of main clause) chains two agents with te-form. わかった? is the past form of 分かる ('understood?') as a casual check-in.