This is the 274th most frequent French word.
petit
Small.
Here, 'petit' is used as an adjective meaning 'little' or 'small', modifying the noun 'chat'.
Le petit chat dort sur le canapé.
The little cat sleeps on the couch.
In this case, 'petit' describes the noun 'problème', indicating it's minor or not significant.
C'est un petit problème, ne t'inquiète pas.
It's a small problem, don't worry.
Here, 'petit' is used predicatively to describe the subject 'je', meaning 'small' or 'young' and referring to childhood.