Isis was the goddess of families and magic. She was the sister and wife of Osiris and the mother of Horus. She is usually shown as a woman with a throne symbol on her head. The throne is part of her name.
Sometimes she is shown with the same headdress as Hathor, the sun surrounded by cow's horns. In the picture on the left, we know this is Isis because her name is next to her (circled in red).
Isis features in the myth of Osiris. When Osiris was murdered and cut up into 14 pieces by his brother Seth, Isis found all the pieces and used her magic to bring him back to life. Later on when Isis bore her son Horus she had to use her magic again to protect him or cure him from the bites of nasty creatures like snakes, crocodiles and scorpions.
Isis was often shown with her infant son Horus - see below.