This is the 111th most frequent Turkish word.
son
"Son" in Turkish means "end" or "final."
Here, 'son' is used as a noun modifier meaning 'last' as in 'the last time'.
Son gördüğümde hava çok güzeldi.
When I last saw it, the weather was very beautiful.
In this sentence, 'son' is used as an adjective meaning 'final' or 'last' in terms of sequence.
Onun son eseri büyük bir başarı kazandı.
His last work achieved great success.
Here, 'son' is used as a noun meaning 'child' or 'offspring' (a borrowed use from English, but understood in a similar context).