Tabs are collections of windows. They are not like browser tabs. Create a new tab with :tabnew
Move forwards and backwards in the tablist with :tabp and :tabN
Move to first or last tab with :tabfir and :tabl
:tabs will list out the tab pages
Go to the last viewed tab with gT

Further Reading

:h :tabnew :h gT :h :tabs :h :tabfirst :h :tablast :h :tabprevious :h :tabNext

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