I. PTO¹ /ˌpiː tiː ˈəʊ $ -ˈoʊ/
(please turn over) written at the bottom of a page to tell the reader to look at the next page

[TahlilGaran] Dictionary of Contemporary English ▲

II. PTO² noun [countable]
American English (Parent–Teacher Organization) an organization of parents and teachers that tries to help and improve a particular school Synonym : PTA British English

[TahlilGaran] Dictionary of Contemporary English ▲

PTO
Please Turn Over - written on a piece of paper to tell someone to look at the other side
I wrote PTO on the last page of my essay to make sure that the professor would look at the last page.

[TahlilGaran] English Idioms Dictionary ▲

PTO
Paid Time Off 
Parent-Teacher Organization (variant of Parent-Teacher Association) 
Patent & Trademark Office 
Please Turn Over

[TahlilGaran] Acronyms and Abbreviations Dictionary ▲