たのしい
fun
tanoshii
JMdict 1207240
りょこう旅行travelはたのしい楽しいfun
は (topic) raises 旅行りょこう (travel) as the topic — “as for travel…”. The い-adjective 楽しいたのしい (fun) then works as the whole predicate, with no “is” verb needed. No polite です (is), so it sounds relaxed.