SSS is side-side-side
for example: they give you a triangle with side lengths - 3cm, 4cm, 5cm
This would be SSS
SAS is side-angle-side
for example: they give you a triangle with a side length, angle measurement, and a side length - 3cm, 45 degrees, 5cm
This would be SAS
I attached a picture so that it helps you more.
HOPE THIS HELPS!!!! :)