Repeat row data based on countcolumn

Two nested foreach loop should do that. The outer one on the rows, and the inner one on that count column.

Like Stefan mentioned, nested forEach will do the trick 

a!localVariables(
  local!data: {
    { col1: "A", col2: "B", count: 4 },
    { col1: "C", col2: "D", count: 2 }
  },
  a!flatten(
    a!forEach(
      items: local!data,
      expression: a!localVariables(
        local!col1: fv!item.col1,
        local!col2: fv!item.col2,
        local!count: fv!item.count,
        a!forEach(
          items: enumerate(local!count),
          expression: { col1: local!col1, col2: local!col2 }
        )
      )
    )
  )
)