A labour-intensive industry or job needs a lot of workers to get the work done. Picking fruit, sewing clothes in a small workshop, caring for patients — these often need many people for each thing produced. The contrasting idea is capital-intensive: you spend on machines and money, so you need fewer people. Though actually, students often hear labour and think this means the work is painfully hard (laborious). It does not. The work might be simple; the point is the number of people. In business talk people also stretch it a little: “This project is labour-intensive” can just mean it will eat a lot of staff time. This spelling with labour is British and is common in Taiwan textbooks; American English writes labor-intensive.