看到 is a resultative verb compound (动结式) formed by 看 (to look) plus 到 (to arrive/reach). It means 'to see successfully' or 'to catch sight of' — emphasizing that the act of looking achieved its result. Unlike 看见 (which focuses on the visual perception itself), 看到 often implies a deliberate effort or a specific moment of noticing. You can also use the potential complement forms 看得到 (able to see) and 看不到 (unable to see).