Imagine a big boat called an ark that was built a really long time ago by a man named Noah. Noah was told by God that there was going to be a huge flood that would cover the whole earth, and that he needed to prepare the ark and bring two of every kind of animal with him.
Noah had a wife, three sons named Shem, Ham, and Japheth, and their wives, who all boarded the ark with him. When the flood came, the ark floated and kept them safe until the water went down.
After the flood, people started having children again, and Noah's family started to grow into many generations. The people who were born after the flood were called the descendants of Noah.
The descendants of Noah’s sons Shem, Ham, and Japheth, who also had children, became different groups of people like the Jewish people, Egyptians, and Greeks. These groups migrated all over the world and their languages and cultures developed over time creating the different races, religions and nationalities of people that we know today.
So, the generations of Noah are all the people who came from Noah and his family after the flood, and their descendants who spanned many centuries and eventually became different groups of people.