The word "great" is similar to "good." You can use it as an adjective to describe people or things.
We’re having great weather these days.
This worked out great. (When used as an adverb, "great" is similar to "well.")
Abraham Lincoln was a great President.
This cereal tastes great.
That movie we saw last night was great.
That color paint looks great on the walls.
We got a great deal on a car.
I feel great today!
He has some great news he would like to share with everybody.
The word "great" is also used in a way that’s similar to the words "very large."
He made a great deal of money last year. (a great deal of = a lot of)
She has a great big headache. (The word "great" in this sentence is similar to "very.")
A great amount of time has been spent on developing this website.
Sometimes the word "great" is used with a bit of sarcasm*:
Oh great. Now we have more work to do.
The cat broke the lamp. Isn’t that just great?
You want to leave early today? That’s great. Who’s going to finish your work?
Sarcasm: You say something but the meaning is quite different or the opposite of the regular meaning. People use sarcasm when they are angry about something or want to exaggerate an idea.
He has some great news he would like to share with everybody.