An inexpert person does not have the skill to do the job well. It is not a word for “stupid.” It only says the skill is not there yet, or not there for this task. You can also call the work inexpert: a job done without much skill. The word is fairly formal, and a little old-fashioned. In speech, people more often say “not very good at it,” “unskilled,” or “inexperienced.” Though actually, inexpert and inexperienced are not the same: inexperienced is about how little time you have had; inexpert is about the skill you show right now. A person can be new and already quite expert, or long practised and still inexpert. Today it is almost always an adjective. Using it as a noun (“an inexpert”) is rare.

不熟練的、外行的（偏書面；口語較常說不太會、沒經驗）