The default terminal in Ubuntu is gnome-terminal. It can be installed with:

sudo apt install gnome-terminal

You can do a search for lists of alternative terminals, though there's a small list on Wikipedia.

I don't want to favor any particular site, so here is one such link.

One oft mentioned favorite is Terminator for the feature set. You're not limited to one terminal emulator, you can install as many as you'd like and then pick which suits your needs most.