[Help-bash] how to understand the xargs

[lina]

Hi,

I don't understand the xargs well,

can someone help me understand the below sentence,

ls . | xargs -i -t cp ./{} {}.bak

How does xargs work,

I checked google, :
-i : replace the string
-t print
but still lack well understanding,

how those xargs organise things,

and
$ ls .
a.txt b.txt

above will give a.txt.bak b.txt.bak
ls | xargs -i cp ./{} {basename {}.bak}
definitely not work,

Thanks with best regards,