데요 I keep seeing this ending but I can't find

데요 I keep seeing this ending but I can’t find an explanation for it in K dictionaries or anywhere else.

데요 is 데+요.
요 is the ending of 해요 as you may know.
it’s for explaining speaker’s thought or his/her own experience.
for example,
프랑스에 가려 했는데요.
=I meant to go to France.
내일 친구를 만날 건데요.
=I will meet my friend tomorrow.
그 남자애는 키가 큰것 같은데요.
=I think the boy is tall.

On the other hand,
there is 대요 which is the abbreviation of -다고 해요
it’s to explain thought or experience you’ve heard or seen.
내 친구가 프랑스에 간대요.
=My friend meant to go to France.
내 동생은 내일 친구를 만난대요.
=My brother will meet a friend tomorrow.
내 여자친구는 그 소년이 키가 크대요.
=My girlfriend thinks that the boy is tall.

I wish my poor explanation gave you some idea.

You might want to check this out as well: Sign in ‹ Learn Korean with Talk To Me In Korean — WordPress.

As you will see, it’s quite difficult to explain with just one translation.