Three sons of Noah entered the Ark with him in Genesis.
Genesis names the sons as Shem, Ham, and Japheth. The Flood narrative says Noah entered the ark with his wife, his sons, and the wives of his sons, making the family group eight people in total when Noah and his wife are included.
The three sons are important figures in the chapters following the Flood. Genesis 9 describes an incident involving Noah and his sons, and Genesis 10 presents a “Table of Nations” that traces peoples to their descendants through Shem, Ham, and Japheth.
The text does not call one of the three the eldest in a simple, unambiguous way. It also does not name Noah’s wife or the wives of the sons. Those omissions are why the safest answer to the question about the number of sons is the explicit number three.