A: There were so many people there today.
B: Yeah, it's mental. X > Yeah , it is a big thing
A: He is a very ....(important) person.
B: Yeah, big time. X .> Yeah , he is big time.
How to understand "It's mental" and "Big time"？
" It's (a ) mental( thing )" >something that has to do with how you feel /or something to do with his mind
"It's big time" >somthing that is of a high level.
Example > The problem she has is all mental , but if she does not control , it can be a problem big time