You add a new row by clicking in the New row line at the bottom of the table and starting to type. The row always stays at the bottom, even when you scroll in the table.
How to do it
Go to the bottom of the table. It says New row – Click in the row or start typing to add.
Click in the cell for the column you want to fill in first, for example Name.
Type the value. The row is added to the table.
Fill in the rest of the cells in the row.
Click Save changes at the bottom of the table.
Good to know
If you are adding many rows, paste them from Excel with Ctrl+V instead.
Read-only tables don't have New row, because they can't be edited.
In some modules you still add new records with a separate button at the top, because they have several fields that must be filled in in a dialog. In Change Order you use + Change Order Client, for example, and in Invoice + Invoice.