5GHz is for speed. 2.4 GHz is for range.
2.4 GHz and 5 GHz are frequencies that different wireless devices use. They differ in range (distance data can travel) and bandwidth (speed). Think of 5 GHz as a fast sprinter and 2.4 GHz as a slower, long distance runner.
5 GHz is a higher frequency, which means your data travels shorter distances quickly but cannot travel through large, solid objects–like a thick wall.
2.4 GHz is a lower frequency, which means your data travels further distances, but at a slower speed. Sometimes, this low-end frequency can get “crowded” by other common devices such as microwaves, garage door openers, and cordless phones, which can translate into interruptions for your connection.