The word "kahf" means "the cave in the mountain"

the sura is named "kahf" because it speaks about the story of the Companions of the Cave

The cave of Ashab e Kahaf is located in Jordan.

Ashab e Kahf slept for 309 years

The number of Ashab-e-Kahf was 7

The story of Ashab al-Kahf is narrated in the eighteenth chapter of the Quran, called “al-Kahf”  In verses 9-26