Open Edit PDF text and choose your PDF. The editor opens with big coloured buttons at the top: Edit text, Add text, Picture, Sign, Highlight, Erase, Draw, Shapes, More.
Tap Add text, then tap an empty place on the page and type. Use the panel to change Font, Size, Color and B / I / U.
Drag the item to move it. Drag the round corner dot to make it bigger or smaller.
When finished, tap ⬇ Download at the top to save the edited PDF.