Normally, we don't use continuous tenses with "to be" verb.
For example, we say "she is beautiful", not "she is being beautiful".
However, the dictionary says
To be 6 [linking verb] to behave in a particular way
He was just being rude.
Don’t be silly.
You’d better be careful.
So, when "to be" means "to behave in a particular way", we can use continuous tenses with it.
However, I don't know in which situations and with which adjectives we can use "to be" in continuous forms
For example, can we say?
-"She is being silly/stubborn/friendly"
-"you are being naughty/bad/spoiled" (talk to a boy)
If yes, then what is the difference between?
-"She is being silly/stubborn/friendly" vs "She is silly/stubborn/friendly"
-"you are being naughty/bad/spoiled" vs "you are naughty/bad/spoiled"