how many security upates for this update

Greetings John_Sia,

Thank you for using Apple Support Communities, it's great to have you here.

We're not sure exactly which update you're referring to but we think that this article has some great information that should be helpful to you: Apple security releases - Apple Support

Thank you for being a part of the community here. We hope this information helps!

Best wishes.

2, according to the link to the document above your name.