It's called System Monitor.

Try btop. apt install btop. If you run it with sudo you can kill processes that are misbehaving

Most likely. Ubuntu has one.

`htop` is a popular command line tool for it in an interactive way. You may need to install it. `ps` is the more standard tool for listing processes in a non interactive way. See `man ps` for usage. `kill` is the command to stop processes. There may be something graphical these days but why?