To merge and center cells in Google Sheets, follow these steps:
Select the range of cells you want to merge and center. To do this, click on the cell and drag the mouse over the desired range of cells.
Right-click on the selected range of cells and click on "Merge cells" in the context menu. Alternatively, you can use the keyboard shortcut Ctrl + Alt + M (Windows) or Command + Option + M (Mac) to merge the cells.
After merging the cells, click on the "Merge & center" button in the toolbar. It looks like a square divided into four smaller squares.
Alternatively, you can merge and center the cells using the Format menu:
Select the range of cells you want to merge and center.
Click on the "Format" menu at the top of the sheet.
Hover over the "Merge cells" option, and then click on "Merge all."
Next, hover over the "Align" option in the Format menu, and then click on "Merge vertically" or "Merge horizontally" to center the merged cells accordingly.
This will merge the selected cells into one cell and center the content within the merged cell.