V + 더라고요 can mean 'because' or 'I learned/found/experienced that...' It is based on firsthand experience or realisation of something:
한국말은 말하기가 어렵**더라고요.
**I've learned that speaking Korean is difficult.
전은 아주 기름지더라고요.
I've found Korean pancakes to be very greasy.
어휘
초밥 -- sushi (lit. small rice)
새로운 -- new (adjective)
어떤 게 -- which one/thing
중에서 -- among
말고는 -- other than (from 말고 -- instead)
-- 오사카 음식 중에서 어떤 게(것이) 맛있었어요?
-- Among the foods in Osaka, which ones were delicious?
-- 타코야키가 맛있더라고요.
-- I found that Takkoyaki was delicious.
-- 타코야키 말고는 어떤 게 맛있었어요?
-- Other than takkoyaki, which foods were delicious?
-- 초밥가 맛있더라고요.
-- I found that sushi was delicious.
겨울에 한국 날씨는 진짜 춥더라고요.
During the winter, I find that the Korean weather is really cold.