When the number of text or text sizes is more than the cell width at that time Shrink to fit option is used to adjust the text size as per cell width.
Tag: Merge Cells
MS-EXCEL-009-Wrap Text | Cell Content in Multiple Lines | Merge Cell | Unmerge Cell | MS Excel-Hindi
Wrap Text options , wrap extra-long text into multiple lines. Merge & Center option, combine more than one selected cell into one large cell.