Pictorial push pull signs for doors are intended to avoid confusion. In English the words "PUSH" and "PULL" are both four letters long and contain the same first two letters. They may occasionally be confused by people in a hurry. For people with dyslexia the chances of error may be even higher.
Pictorial push pull signs for doors Wikipedia
In international cities, there will be foreign visitors who do not necessarily speak the local language. Regardless of language, a picture is sometimes more noticeable and more quickly understood than words.
The initial ideas in the design of the push pull door pictograms were to use an image of a hand for "Push". Research confirmed that a symbol of a hand is used for "Stop", "Halt", or "No Public Access", and these hand image symbols are widely used in the construction industry. Red indicates caution as "pull" is the direction in which accidents happen. (Kleine Beitel study 1994). The changes to green and red were made following the study from Oxford Brookes University, Psychology Dept on the human pictograms (Prof. Angus Gelatly and Meera Dulabh 2012).