Check out example codes for "sheets column number to letter". It will help you in understanding the concepts better.

Code Example 1

SUBSTITUTE(ADDRESS(1,column number,4),"1","") turns a column number into a letter
	SUBSTITUTE(ADDRESS(1,2,4),"1","") gives B

ADDRESS(1,column number,4) turns two values into an address
	ADDRESS(1,2,4) gives B1
    ADDRESS(2,1,4) gives A2
    ADDRESS(2,1,1) gives $A$2
SUBSITUTE(address,"1", "") subsititutes the "1" with "", removing it.
	SUBSITUTE(B1,"1", "") gives B

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