to save: to step in on behalf of someone in danger, distress, or the wrong, and bring them through to safety, victory, or vindication.
At its core this word is about intervention: someone in trouble, and someone else who shows up and does something about it. It reaches across the whole work of coming to the aid of the imperiled, from pulling a person out of immediate danger, to winning the battle that frees a people from those who oppress them, to standing up for the weak or the wronged who cannot defend themselves, and, on the receiving end, being brought safely through.
A long tradition claimed the word originally pictured being brought from a narrow, cramped place out into open space, and popular teaching still repeats it. Careful study of the word's history has set that aside: there is no reliable underlying image of width here. The word simply names the act of helping and rescuing, and the frequent pairing with words for distress and being hemmed in is a natural association, not the buried meaning of the word itself.
In most of the Bible the one doing the saving is God. He is the deliverer of Israel at the sea, the rescuer of the person who cries out in trouble, the one who gives victory when the army is too small to win on its own. The judges and kings who save do so as his agents, and the prophets press the point that no one and nothing else, no idol, no foreign alliance, no horse and chariot, can actually do it. In Isaiah the human rescuer drops away entirely: God insists that besides him there is no savior at all.
This is the word that stands behind the most familiar language of rescue in the Hebrew Bible. The personal names Joshua and the later form Jesus mean "the LORD saves," and the noun usually translated salvation comes straight from it. Yet on its own the word is concrete and this-worldly: rescue from real enemies, real danger, real defeat. The later idea of saving the soul is where the trail eventually leads, not where it begins.