Replace data in a whole column as Excel

I’m new in Powershell.
Well, with Excel I can select a column and repalce multi characters in 1 second. I would like to do the same thing with Powershell. With Excel it looks like this :

Sub Macro1()
    Selection.Replace What:=" on ", Replacement:=";", LookAt:=xlPart, _
        SearchOrder:=xlByRows, MatchCase:=False, SearchFormat:=False, _
End Sub

I know how to do it when it is like this : (what:=""), but not for " on " (with space before and after “on”.
Could you please help me ?

This was two days I was looking, I found, here is the solution:

 $ range.EntireColumn.Replace (‘on’, ‘;’) 
Thank you.