If the text is in a table cell, you need to tap the cell before you can select the text.
Select a word: Double-tap it.
Select a paragraph: Triple-tap in the paragraph.
Select an item in a list: Tap its bullet, number, or letter.
Select a range of text: Double-tap a word, then move the grab points to include more or less text. Drag beyond the end of a paragraph to include any formatting marks (called invisibles).
Note: If you tap placeholder text, the entire block of text is selected.
On iPad, you can also drag two fingers across the keyboard to move the insertion point, then tap once on the keyboard to select a word and twice to select a paragraph.