When someone got better from sickness
How can i say? Just wanted to know natural way to say.
for example, I glad to hear you got better, That's relief you got better, etc.

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A good one is: "(I'm) glad to hear you're better." You almost got it yourself.

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I agree with Michael, "I'm glad to hear you got better."

The formal word for "getting better from sickness" is "recovery."

"I'm glad to hear you've recovered from your surgery." 
"So-and-so has made a full recovery from his rotator-cuff injury." 
"How long does it take to recover from a sprained ankle?"