Go on, count them...
How many tentacles does an octopus have? None.
Octopuses are named for their eight limbs, known generally as arms. Their cousins, the squid and cuttlefish, have eight arms plus two tentacles.
These two limb types look and behave very differently. Tentacles shoot out and catch prey with suckers at the end. Arms have suckers all the way along and are used to sense the surroundings, search for food and sometimes walk.
It’s too simplistic to claim that octopuses have six arms and two legs. All eight are multipurpose tools. However, octopuses tend to reach out to touch things with a preferred front arm and use two rear arms when they go for a walk.