Extracting A File Name From A Path

Formula:

=IF(ISERR(FIND(" ",B25))*LEN(B25)-LEN(SUBSTITUTE(B25," ",""))=0,B25,RIGHT(B25,LEN(B25)-FIND("*",SUBSTITUTE(B25," ","*",LEN(B25)-LEN(SUBSTITUTE(B25," ",""))))))

The formula on B25 extract the last word from the string on A25.

Can you explain the logic of the formula, how it works?