"Ecstatic" means really, really happy. Things that might make a person "ecstatic" include:
- winning the lottery
- getting an amazing job
- getting engaged
"Ecstatic" is an "ungradable" adjective. It's similar to these:
Adjectives like these shouldn't be used with adverbs like "very" or "a little". That's because "very" is already included in the meaning of the word.