Calculate Variance (statistics): math / statistics - someone who already know how to do it

Using the attached 2 data sheets, please calculate variance and explain, as soon as possible, ideally, in the coming one hour or two. Please make sure you know how to do this, instead of, "I can learn quickly" - This must be completely accurate.

In the mail you ask me to choose you to do this work, please tell me the following:

Tell me what "calculating variance means in statistics

Please first take a look at sheet 2 and sheet4, and tell me if those charts give you enough data to calculate variance.

Thank you.