noun
A person involved in politics, especially as an elected official or prominent figure. Can carry a neutral or slightly formal tone.
彼は将来、政治家になりたいと思っている。
He wants to become a politician in the future.
その政治家は
The politician spoke about environmental issues in his speech.
Specifically a member of a legislative body (Diet, assembly). 政治家 is broader and can include non-elected political figures.
Compound of 政治 (politics) + 家 (person who does that as a profession).