As sophie said Hi or Hello .You can understand it even if you do not speak French ( a bit of maths is enough ,hehehe) : Salut + ation = salutation.

Hi

yeah salut is mean hallo in french

salut .it's taken from (salutation ) = français .by english (greeting)

"Salut" means "Hi!" but you can use it if you're leaving too (like "Bye!")