You can convert selected paragraphs to a table. Columns will be created automatically at tab characters in the text. Note that you cannot convert text to a table inside another table.
Context menu: Direct conversion without a dialog
Right-click on the selected text and select Convert text to a Table in the context menu. This uses the default table format directly. You can configure the table afterwards with the Properties tool in the Table tab.
Table tool: Configure the table with a dialog
Select the paragraphs you want to convert and then select the Table tool in the Write or Table tab. Before the table is created the table properties dialog is displayed with which you can configure all table attributes except the number of columns and rows. Those are based on the selected paragraphs and the tab characters they contain.