Poly cotton fabric is a mix of polyester and Cotton (Cotton is a natural fibre from the cotton plant & polyester is a synthetic fibre usually made from petroleum)
The amount of polyester that is combined with cotton to make the fabric varies but is usually about 20% polyester & 80% cotton.
It is a light weight fabric which is really versatile and durable, it can be used for dressmaking, patchwork and bedlinen as well as lots of other craft projects.
It is usually cheaper then 100% cotton fabric which makes it a great alternative to 100% cotton fabric if working on a budget.
Poly cotton does not require much in the way of special care, being easy to machine wash and it doesn't crease easily unlike 100% cotton which tends to crease more. Take care when ironing however. Don't use a very hot iron as the polyester can melt if subjected to a high temperature.
The disadvantages of poly cotton are that it is usually a lighter thinner fabric. It is not as breathable as 100% cotton fabric making it a poorer choice for clothing in hot weather. Some poly cotton fabrics also don't hold the dye quite as well as 100% cotton so take care when washing bright colours with paler colours as there can sometimes be some leaching of colour in the wash.