This is the 5759th most frequent Turkish word.
sağlığın
"Your health."
The word 'sağlığın' here is used to mean 'your health,' indicating possession of 'health' by the second person singular (you).
Sağlığın için bol su içmelisin.
For your health, you should drink plenty of water.
In this sentence, 'sağlığın' again refers to 'your health,' used possessively when inquiring about someone's health status.
Sağlığın son zamanlarda nasıl?
How has your health been recently?
Though not using 'sağlığın,' the sentence uses 'sağlığını,' showcasing how the root 'sağlık' is modified to indicate possession (your health) and acted upon as an object ('maintaining your health').