Annualized ex post standard deviation

Lot of GIPS standards has this “3-year annualized ex post standard
deviation” requirements and recommendations.
can someone please explain what is that exactly?

thank you!

You look back (ex post) at three years of (say, monthly) returns and compute the standard deviation of returns. If the data aren’t annual, then you convert them to annual data (e.g., the annual standard deviation would equal the monthly standard deviation times √12).

ohh alright,understood!
thank you so much!