And hath raised up an horn of salvation for us in the house of his
servant David; (Luke 1:69, KJV)
καὶ ἤγειρεν κέρας σωτηρίας ἡμῖν ἐν οἴκῳ Δαυὶδ παιδὸς αὐτοῦ (Luke
The word σωτηρίας/sōtērias (KJV: of salvation, Strong's G4991) is a genitive feminine singular noun in Greek. As a genitive, it indicates a possessive case, which is why the "of" goes with it.
For if, when we were enemies, we were reconciled to God by the death
of his Son, much more, being reconciled, we shall be saved by his
life. (Romans 5:10, KJV)
εἰ γὰρ ἐχθροὶ ὄντες κατηλλάγημεν τῷ θεῷ διὰ τοῦ θανάτου τοῦ υἱοῦ αὐτοῦ
πολλῷ μᾶλλον καταλλαγέντες σωθησόμεθα ἐν τῇ ζωῇ αὐτοῦ (Romans
The word σωθησόμεθα/sōthēsometha (KJV: we shall be saved, Strong's G4982) is future-indicative passive voice verb in the first-person plural. The future-indicative gives it the "shall", the passive voice gives it the "be" + past participle ("saved"), and the first-person plural gives it the pronoun "we".
Salvation is the gift we receive from God through the action of being saved (passive voice, because God is doing the saving, not us).