Saved out of Egypt means they were delivered (saved out of Egypt). It doesn't mean they were all saved by grace through faith. The Lord delivered His people (the Israelites) out of Egypt, but later destroyed those who did not believe (Jude 1:5). Nothing is mentioned here about them previously believing and being saved, but now they stopped believing and are no longer saved, but lost.
It means exactly that. Israel was saved out of Egypt by grace through faith. GOD passed over the judgment rightfully due them IF they had faith in GOD's command to apply blood of a lamb on their dwelling. That is grace. They didn't earn their salvation; it was a gift of GOD because of his faithfulness to his covenant with Abraham, Isaac and Jacob.