It mean you not act your age. Having or showing emotional or intellectual development appropriate to someone younger.
Immaturity is a noun.
Immaturity(;
The hormone that causes sexual immaturity when deficient is the sex hormone. For women especially estrogen deficiency can cause sexual immaturity.
Both are grammatically correct, but for the sake of flow of the sentence immaturity will do.
immaturity
Immaturity.
The prefix"im" indicates the negative of the word maturity and the suffix "ity" indicates a state of being in relation to the adjective "mature", which is the base word of immaturity.
The immaturity of the human brain.
Insecurity and immaturity.
immature
Time will do it for you. Just relax.
you will never hit puberty