If you use ssh very often, or if you are using git and github on ubuntu, you might want to generate ssh keys on your computer.
To generate ssh keys on ubuntu is quite easy to do, there is a command called ssh-keygen that will generate ssh keys for us.
Before running ssh-keygen, why don't you goto .ssh/ folder on your home directory and see what's inside.
If you found id_rsa and id_rsa.pub that means you already have ssh keys, no need to generate another one.
One of the benefit of having ssh keys is that you copy your public key (id_rsa.pub) to file called authorized_keys (under .ssh folder) on the ssh server, by doing this you no longer need to enter password every time you connect to that ssh server.