This is an exclamation. The writer is saying what he wishes or longs for God to do. Alternate translation: "I wish so much that the salvation of Israel would come from Zion!" (See: [[rc://en/ta/man/translate/figs-exclamations]])
Here "the salvation of Israel" is a metonym for Yahweh, the one who saves Israel. Alternate translation: "Oh, that Yahweh would come from Zion and save Israel!" or "I wish that Yahweh would come from Zion and rescue his people Israel!" (See: [[rc://en/ta/man/translate/figs-metonymy]])
These two phrases mean the same thing. Here both "Jacob" and "Israel" represent the people of Israel. The two phrases can be combined in the translation. Alternate translation: "then all the people of Israel will rejoice greatly" (See: [[rc://en/ta/man/translate/figs-parallelism]] and [[rc://en/ta/man/translate/figs-synecdoche]])