例えば、フランス人ならロシア人のジョークを聞いてもなかなか笑えないかも知れない。

、。

For example, a Frenchman might not easily laugh at a Russian joke.

Literal

For-example, French-person [if-なら] Russian [of-の] joke [object-を] hear-even [easily-なかなか] might-not-be-able-to-laugh.

なら is the presentational/hypothetical conditional ('if it's a case of X, then…'). なかなか + negative = 'not easily, not readily.' 笑えない is the negative potential of 笑う. ~かもしれない ('might, perhaps') wraps the whole thing as speculation. A classic cross-cultural humor observation.