I just started stats, and im kind of confused about SD. I know how to find it, but dont really understand what, for example, SD of 2.5 means.

Can someone explain?

Heres an example of a question I dont understand.

Is the SD of the number of years of college professors teaching experience:

6 months

6 years

16 years

Can someone tell me and explain why...in easy terms?

Id really appreciate it!