It could be "people's" with an apostrophe before the s. Meaning something belonging to a group of individuals (the something in this case is the turf). For example "Most people's experience of learning another language is..."
But it could be "peoples' " with an apostrophe after the s. Meaning something belonging to a group of tribes/ethnic groups/nationalities. For example "Most native American peoples' experience of meeting European settlers was..."
It depends on the context.
"Turf" has a number of meanings. In this example it is a synonym for territory/area inhabited