You can decide to have a table without or with border lines. 

A table without border lines is used to position text and pictures on the screen as seen in the picture of the children in hospital.  Those lines will not show when viewed with a web browser.

A table with border lines is used to tabulate information as seen in the names of towns.

To insert border lines select the table then click on Table, then Properties and then Table Properties.

If you do not wish to have a border give it the size 0. The higher the number the wider the borderline.  If you wish to colour the border select the required colour.