I am studying about calculation of standard error. It's formula is :

```
standard error = standard deviation of population / square root of n

```

If we do not know the standard deviation of population, we use standard deviation of sample.
But we draw multiple samples, so we can calculate multiple standard deviation from those samples. Which one of it should be used in standard error formula ?

I checked couple of youtube videos. They just tell us to use standard deviation of sample but none of them tell which sample ? Can anyone clear my doubt about this ?

Thanks in advance.