Of course it is a Tarball, that is the format most things are distributed in for Linux. There is also an option to download it in a flatpak or a snap version. But generally on Linux, unless you are determined to do things out of band you use your distributions package manager app to install all programs. Give from your question that you are probably completely new to the Linux ecosystem and as Ubuntu is one of the more popular distributions for Linux newcomers I will take a punt that is the distribution you are using. See https://www.wikihow.com/Install-Software-in-Ubuntu

See also https://support.mozilla.org/en-US/kb/installing-thunderbird-linux