Select the row below where you want the new row
Right-click the selected row
Click Insert
Or select a cell in the row and press Ctrl + Shift + +
Or go to Home > Insert > Insert Sheet Rows
To add multiple rows, select the same number of existing rows first, then insert
On Mac, use Command + Shift + + if available
In Excel tables, right-click a cell and choose Insert > Table Rows Above or Below