The syntax of the SUBSTITUTE function
=SUBSTITUTE(text, old_text, new_text, [instance_num])
This is a little different from the last syntax we looked at, so be careful not to get them mixed up.
text is the cell that contains the string you want replaced.
old_text is the sequence of characters that you want Excel to replace.
new_text is what Excel will insert in its place.
instance_num is optional, and tells Excel how many times it should replace old_text if it finds more than one instance.
We’ll take a look at that last one in a moment to clear it up.