but, however
The particle でも is used to express a contrast or exception, similar to 'but' or 'however' in English.
Examples
この映画は面白いけど、長いです。
This movie is interesting, but it's long.
明日は雨が降るけど、出かけます。
It will rain tomorrow, but I will go out.
お金がないけど、買い物に行きたい。
I have no money, but I want to go shopping.
Quick check
この映画は面白い___、長いです。