What is the meaning of 'Am Yisrael Chai' that Israel used in its tweets?

Israel used the phrase 'Am Yisrael Chai' in its tweets after Iran attacked the country. The phrase, which means "The people of Israel live", is a slogan of Jewish continuity and resilience frequently invoked in moments of communal hardship. There is a 1945 recording of liberated Jews of a Nazi concentration camp in which the phrase can be heard.