Bonjour !
a. Someone who believes he/she is really good at something => self-confident
b. Someone who doesn't like talking in public and is very reserved => shy
c. Someone who does well at school and is very intelligent => clever
d. Someone who doesn't talk about his/her achievements => modest
e. Someone who doesn't like new ideas or opinions => narrow-minded
f. Someone who works with a lot of dedication and energy => hard-working
g. Someone who likes to socialize and be with other people => outgoing
h. Someone who is not very intelligent => dumb
J'espère t'avoir aidé. Bon courage !