* Arcturus is much, much larger than our sun. Arcturus is a red giant star, meaning it has expanded greatly after exhausting its core hydrogen fuel. It's about 26 times wider than our sun, and its volume is 17,576 times greater than our sun's volume.
* Stars are not solid objects. They are giant balls of plasma, held together by gravity.
So, while you can't physically fit our sun into Arcturus, you can imagine that 17,576 suns could fit into the volume of Arcturus.
