SUBSTITUTE function is used to replace a specific text in a text string. For example, you can replace an article “a” with “the” in the text string. It is case-sensitive and does not support wildcards.
SUBSTITUTE(text, old_text, new_text, [instance_num])
text – It is a text or reference of a cell in which you will replace characters.
old_text – The text that you want to replace.
new_text – The new text that you want to replace with old_text.
[instance_num] – Optional. It is used to locate the location of the text to replace, for example, in “Apple” if you only want to replace letter “e” then you will type 5 against instance_num. In case you leave it empty then Excel will replace all characters including both “e”.