Mis forMat
A mat is a piece of fabric, usually made from something quite firm like woven rushes. Mats come in different sizes depending on what they are used for. Doormats are used to wipe your feet on outside a door, placemats are used for protecting a table as you eat, and various sized floor mats are used in indoor sports as a soft surface over a hard floor.
The woman in the picture is on a yoga mat.