I would appreciate any help that you Excel gurus could provide.
I have a customer that has recently requested some training with us. I'm
very familiar with Excel and teach the typical Excel Level 1, 2 and 3 courses.
The customer has used some terms that I'm not familiar with.
What do these mean? I have checked the web but still not clear on some of
them.

1) The customer wants me to cover advanced functions using the expression
builder. They have listed Confidence expression, Frequency and ST Deviaton.
What exactly is the expression builder? Is this another term for a standard
feature that is known by another name?
2) Using statistical expressions in the expression builder: Again, what are
they referring to related to this expression builder?

Any help in explaining to me what these refer to would be greatly appreciated.
Thanks!
Juggertwo