Damon-MJE
You didn't give us enough of the dialog to determine what "it" refers to. I had to look up the episode and find the missing reference.
Here it is.
- I saved you a dumpling.
- Oh, your concern
for me is touching.
It will serve you well, when you take me to
the dentist tomorrow.
- I'm sorry, Sheldon, I'm busy.
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It = your concern for me.
Your concern for me will serve you well when you take me to the dentist tomorrow.
will serve you well = will help you or benefit you