This is the 7444th most frequent Chinese word.
行家
Expert; connoisseur.
The word '行家' is used here to mean an expert or someone who is proficient in a specific skill.
他是家具修理的行家。
He is an expert in furniture repair.
The word '行家' denotes someone proficient and knowledgeable in a certain field—in this case, stock market investing.
在股市投资方面，她真是一位行家。
In stock market investing, she truly is an expert.
'行家' is utilized to describe an individual deeply skilled in a certain domain, here, photography.