This function is only available when connected to a Teradata database.
The standard inverse Hyperbolic Cosine function is supported, generating ACOSH (expression) and returning a value of type float. When dragging a Hyperbolic Arccosine operator into a variable, the following tree element is created.
Variable Creation > Input > Variables: SQL Elements pane - Trigonometric > Hyperbolic Arcosine

Columns and/or other expressions can be moved into the (empty) branch of the tree. There are no special properties for the Hyperbolic Arccosine operator.