With the "Linefeed" button, you insert a line break ("¶") into your text line.

 

Figure 10.6: Insert line break by clicking the button

However, such a break only has an effect if you have specified that breaks are allowed for the object in question (line of a text object or column of a table object). In this case, the words that don't fit in the line/column are continued on a new line causing the lines below to be moved down by one line. (Caution: If the text contains just one long word, it will not be broken but will be truncated instead).

With text objects, the value of the "Line Wrap" property in the property list for the respective paragraph must be "Wrap".

With table objects, the value of the "Fit" property in the property list for the respective column must be "Wrap".