Sherut Leumi is national service. It is most often performed by young ladies after they graduate high school, in lieu of going into the army. I think the girls can be a “bat sherut” up to three years; my middle daughter is in her second year.
The jobs can be almost anything – working in hospitals or old age homes, in schools, working with special needs kids, working in service organizations, working in museums and historic sites, etc.
While working the girls are given a place to live (usually an apartment with other girls) and a small salary.
Keep in mind that once a girl gets her exemption from the army, she does not have to do sherut leumi. It’s entirely voluntary.