。
I know a good place for dinner.
Literal
Dinner [for-に] good place [object-を] know-[explanatory-んですよ].
Casual conversational opener, perhaps leading into a recommendation. いいところ ('a good place') uses ところ to mean 'place, spot.' 知っているんですよ layers three things: the resulting-state 知っている ('know,' literally 'be in the state of knowing'), the explanatory ~んです, and the assertive よ. The result feels warmly informative — 'you know, I happen to know...'