入境 means 'to enter a country' and is the specific term for crossing a national border (at airports, ports, land crossings). It contrasts with 出境 (chū jìng, 'to leave a country') and 过境 (guò jìng, 'to transit through'). Unlike the general verb 进入 (jìn rù, 'to enter any place'), 入境 is used only for entering a country or region, especially in official and travel contexts.